FSD\PMD - BFD

[gmctd]

Catchy title, to be interpreted literally, not flippantly.

Pre-requisite disclaimer -
I do not intend to reveal actual FSD\PMD logic circuitry, beyond what's necesary to explain failure. The OEM product supplier - not GM, not Stanadyne - is a $4.73 billion in yearly revenue global concern, and I do not wish to involve myself or Jim Bigley and the DP in any 'illegal disclosure' wrangles.

I will offer a hint as to how you can open yours - inside you will find the OEM Company name, legibly etched in copper on the pcb. Contact them - perhaps they will provide a schematic. Perhaps not.

Hint - heat. And, finesse.

First, some background.
Summer of ought one, I encountered the dreaded FSD\PMD 'dies but restarts' failure, after driving the truck over 3 hours with coolant temps around 240deg.
Drove 300mi back to the house at 70mph, pulling the empty trailer, no hiccups for a week.
Then, after several incidents over three weeks - replaced Driver.
I like the PCM management, so I was bound to determine why.
I think I did, and I'll explain, but I could not leave that failed module alone.
So -

The module is not potted strictly as a deterrant to anyone discovering its secrets - that's about 1% of the reason.

The compound is thermally conductive, such that no component should get hotter than any other.

The compound provides physical and thermal shock protection to the components.

The compound is weatherproof, as are the cable connectors - each wire has a silicone rubber seal, as does the connector shell.

Ok - I succeeded in removing the potting from the pca, leaving most of the components intact. Some are very very small, and a few did desolder from the heat. Labels are intact.

I removed the pca from the heat-sink (yes, Dorothy - there is a large cast-aluminum heat sink inside), with printed circuitry intact.
I had earlier removed the drivers by desoldering the Emitter and Base leads, and removing the loose stainless steel screws. These screws fasten the drivers to the heatsink (with kep nuts) thru the pcb Collector circuit pads.

The sink has wells for the drivers, and wells for the epoxied emitter resistor bars, which are soldered to the pcb at those points, and wells for the schottky diode and pre-driver.

The large schottky diode, series in the +12v ignition circuit, is fastened to the heat sink, as is the pnp bipolar pre-driver.
Essentially a darlington configuration, it's Collector is tied to the paralleled Driver Bases, and the parallel Collectors drive the Fuel Solenoid directly.
Emitters are tied to 12v at the schottky cathode via the 'bars', with a pullup resistor from each Base to each Emitter.

5volt logic consists of 'd'-flops, Schmitt-trigger nand gates and associated circuitry.
Components are labeled, except for capacitors - non-electrolytic SMT caps are not labeled. You just get tans, and greys, and blues, and etc.

Ok - no push-pull circuitry. Never did like that term, anyway. From tubes back in the '50s to C-mos and stereos today, turn off the neg device, the pos device pulls the signal to the pos rail; turn off the pos device, the neg device pulls the signal to the neg rail.
The left tube pulled its plate winding to cathode while the right tube was off, then the right tube pulled its plate winding to cathode when the left tube was off. Power thru the center-tap.
Always been pull-pull on my scope. Hah!

C-mos logic chips are closest thing to 'push-pull' in the FSD\PMD.

Next - no one on this website, or any other website on this planet can duplicate the FSD\PMD circuitry for $10 bucks. Well, maybe if you're buying hi-tech electronic scrap for pennies a pound and stripping and culling the parts. May even get some defunct FSD\PMDs in the deal, right?

It's not a simple amp - the darlington config is for fast rise-time, required to get the Fuel Solenoid moving in it's 1.95ms time frame. Travel is only 5thousandths inch, but I checked it for over 30 amps. And that can switch over 200 times\sec at higher rpms.

Failure -
Intermittent, but not dead.
When I removed mine, only one of the four screws was more than finger tight. Not much thermal transfer afforded a loose-mounted heat sink.
Popped the covers off the drivers, and each screw pair was loose, not even finger tight.
When I removed the drivers, the white plastic insulator on each driver was burned to the case where the transistor chip was attached
internally
Both drivers tested ok on static and dynamic frequency function check.

Cause of failure - driver Collector connection is made from case thru two stainless steel screws, fastened with stainless nuts to pads on the pcb. Stainless is not a good conductor of heat or electricity, and with the current required by the Fuel Solenoid, the fasteners should have been solder-plated steel studs, soldered into the pcb, with the nut on the driver case. Professional been there, done that opinion.

Failure compounded (no pun intended) by thermal compound buildup on heatsink at mounting screw locations. Compound crush-settled with heat, causing loss of thermal transfer at silicone pad to FI pump, as screws loosened.

I mentioned, in another post, deteriorating bi-polar specs as causative, also. We documented massive-quantity failures, where transistors would pass static tests, but fail on-board in switching power supplys, then pass static re-tests. 70% dropout, four switchers on each board. OEM claimed innocence.

May have been our $6mil yearly couldn't compete with $4.7bil yearly, and we were getting culls.
This was mid'90s - we switched to FET tech, and resumed normal dropout rates.

Power mos-fets have easier drive requirements, no thermal run-away, easier to parallel un-matched pairs\triples\quadruples, etc, are available inexpensively in hi-volt/hi current specs.

How did I mount my replacement? On the pump, with a few precautions.
Soon's I collect a few more items, it's DB2-4911 time. Why? Price of Tech-II sets - like to have one, but e-bay keeps the prices up.

Plans to design a better Module? Not even.
Would liked to have put mos-fet tech in a new Module, but a TECH-II is needed for in-depth testing.
Don't feel the 'finesse', lately, either.
Hey, I'm 62 - you guys tear it up! ;)

jd

[ 12-04-2003, 05:43 PM: Message edited by: gmctd ]

[turbovair]

GMCTD,
After reading your post(excellent) and employing my limited brainpower, I discern that the:
1. PMD was not mounted securely to the pump
2.Components within the PMD were not mounted securely to promote heat transfer.
3. Certain fasteners within the PMD are not of optimum material to promote heat transfer.
Soooo,
The major cause of all the above would be VIBRATION, more than heat? Am I on the right track?

[BETA]

Thank You gmctd - excellent job

You have just made my day. I had the pressure on me to forward similar information.

Additionally, I know from endurance testing that vibrations are virtually of no concern, in this case.

[StephenA]

Revelations! -Thanks jd, that's quite a glove!
OK, to the point:
Not having actually seen a FSD/PMD (or even a BFD, lately), I feel enlightened. My view from DB2-4911 heaven (gotta love my '92) is that it just isn't fair to allow all these failures to louse up an otherwise useful truck. Perhaps from the data you have most wonderfully discovered and provided us all with, a reliable fix for most/many or even some failed units just might be R&D'd... Long shot? Probably.

But maybe not: If the internal topography of the unit is such that the stainless steel bolts & nuts could be gotten to by removing and replacing a small amount of the thermally conductive potting compound directly covering them, perhaps they could be replaced or tightened, after restoring the spent heat sink compound? Or are the driver cases in the way? If only one side were accessible, is it possible through a bit of drilling or milling, that the screws or nuts could be minimally exposed and then tightened regularly or when ever they become intermittent? Any holes left might be filled with a removable thermally conductive plug or grease for future maintenance? Just a thought.

Discarding the $50-100 worth of parts these things represent every several months/years seems a shame, especially when they are so expensive to replace and needed to keep our trucks running.
If this or some other approach were feasible, the number of discarded units would undoubtedly represent an ample supply for the field, and TDP enthusiasts could fix their own.

With your much appreciated descriptions, I feel now that by exploring a few units, I could come up with an workable approach, if one exists. But since my truck uses the venerable DB2, and since you've already done the work, I figure you would be in the best position to evaluate whether or not this would be a waste of time.

Thanks again,
Toto ;)

[gmctd]

Turbovair - you're on the right track, and heat is the major causative. Vibration does not play a major part in causing the problem, as BETA stated, but would aggravate loosened connection(s).


Beta - I can well identify with that type pressure. If I am accosted on the street for that FSD\PMD info, I will chew up and swallow the pcb. ;)

StephenA - I wasn't ignoring your request for links last night - I spent the entire evening on the post, submitting it around midnite here (don't understand the crazy time stamps I see - 1022pm? I was transcribing, spell-checking, and editing for content at 1022pm. West coast thing?).
Possibly the articles are in the published manuals. The DS-4 article is in the Member's Area now, and that has some pertinent info which can be correlated to the Module.
(By the way - that 'Dorothy' wasn't directed at you. I normally employ 'Vern and Earnest' and 'Tim and Al' and that type humor in my writing. Recent members would not know that, so your humorous response is doubly appreciated.) smile.gif
I fully agree - seems something could be done to determine if recovery is possible with the intermittent-type failure modules. It would require a vehicle with the remote-mount cooler, in wide-open, little traffic area to accomplish.
I certainly would not care to endure repeated stall tests here in Houston traffic.
Would also require driver's accurate failure description on modules sent in for testing.

The Module (neglected to mention - my Module was in a two-piece plastic box, with minimal potting inside) pcb is bonded to the heat-sink when potted.
The heat-sink is a cast-aluminum piece with wells for several devices. A channel runs just in-board of the perimeter, which has raised ridges to support the pcb. The pcb is notched at the corners to clear the Module-to-pump screws.
Potting compound fills these areas beneath the pcb, making replacement of the pre-driver transistor with FET extremely difficult.
If later Module potting is similar to my version, the Driver pair mounting scheme could be reworked in place, as you described.

To re-iterate, several problems exist with this Module. Some may be addressed, others maybe not.

1. Intermittent - stalls, restarts - loose driver transistor mounting screws prevented adequate electrical connection to the pcb Collector
pads.
I = E/R and E = IR Adding 0.1 ohm to that circuit will doom it. 30 amps x 0.1 ohm drops 3 volts. I don't think the Fuel Solenoid is gonna meet its 1.95ms seating deadline.
Bing! Injection pulse width error. Danger, Will Robinson! Danger!
Thermal compression-expansion of the potting compound resulted in poor hi-current connections, and limited Driver thermal transfer to the heat sink.
Stainless steel fasteners are not excellent electrical conductors and are not easily plated to perform this task. Copper-flashed and tinned steel studs, bradded and soldered to the pcb, would be my preference, considering the production assembly procedures required.
Same plating for the kep nuts.

Addressing this failure may simply(?) involve R&R'ing the FSD\PMD, tightening the phillips-head screws.
Remote cooler mounted units would be easy to check\test this theory.

2. Stalls, no restart, dead - could be initiated by the above scenario, where thermal breakdown\secondary breakdown failures were catastrophic.
Would be simple to test for - measure between driver case(s) and pin B Solenoid Drive.
Driver cases should be shorted together, and to Pin B - any resistance would indicate the problem may have started there.
Measure between cases and pin D +12v power - that is the Collector-Emitter junction, which should essentially measure as open in a functional transistor. Shorted is dead.
If Driver case-to-case measures any resistance above zero, the electrical connection thru the screws is bad. It is a direct short in the module.

Could also be blown series diode - no internal power. Resistance test for that requires getting into the pcb.
Could be logic failure - measure each connector pin to the others, none should be shorted.
(I know - I stated in another post that C is common to F Ground, but that was a test - anyone calling me on that would (a - hoped for)know the circuitry, or (b)be expert on Stanadnye FI systems. I did not want to divulge too much at the time, as I had not yet decided to do this post for reasons stated at the top. Maintaining professional responsibility can be difficult, don't you know. Or is it simple paranoia?) ;)

3. All the above - bi-polar transistor specs deterioration. Poor thermal and or secondary breakdown susceptibility, severely mismatched hfe between parallel pairs, etc. One driver, running hotter than the other, fails, the remaining driver overheats and fails. No recovery.

Thanks for the response, guys. It is why I like to post, rather than write an article. The live response brings more info to the table, which ehances the knowledge base.
That's the hoped for result, anyway - I do dread the 'pitchforks and cries of "tar and feathers"' responses. ;)

jd

[ 12-24-2003, 06:17 PM: Message edited by: gmctd ]

[StephenA]

Hi jd,
Thanks for your assistance in finding the earlier links. I'm sure I can find them easily enough now.
I find your humor as refreshing and vital as the hard earned FSD/PMD facts you have discovered and so patiently and generously written up. Hell, the darn thing is so mechanically screwy, not to mention it's commercial, political & legal ramifications, if we can't see the comedy in the situation, I'm quite sure we'll miss the rest of the picture as well. And anyway, you're funny! As to your references to "Dorothy", my wife will be relieved, because I didn't respond to any other name all day yesterday... :D


I fully agree - seems something could be done to determine if recovery is possible with the intermittent-type failure modules. I am happy to hear this, as I am sure everyone else will be, if we can come up with a conclusive approach.

The attachment of the circuit board to the aluminum heat sink by potting compound makes x-raying useless, but no matter, as you have already well established the over-all layout smile.gif , and we can refine our placement of maintenance and testing portals through trial and error with failed units, based on what you have observed.

Folks with multiple FSD/PMD units & remote mountings, such as Bill H (see his post at the tail of the "PSD Electaical Signals Analysis" thread) could easily swap in and test our repairs/upgrades for validity, as long as they came no nearer to Houston than 'umble... (why isn't it 'ouston?) :D

Perhaps the pre-driver transistor leads or traces leading to them could be exposed enough to test, if not cut & re-routed through an FET.


If later Module potting is similar to my version, the Driver pair mounting scheme could be reworked in place, as you described.
So this could allow us to replace the SS hardware with:

Copper-flashed and tinned steel studs, bradded and soldered to the pcb, would be my preference, considering the production assembly procedures required.
Same plating for the kep nuts.
Given a reliable jig and approach, this upgrade could be performed on both new & failed units, thereby addressing

1. Intermittent - stalls, restarts .

The same jig and approach could also provide for machining testing ports which address (2.):

Stalls, no restart, dead - could be initiated by the above scenario, where thermal breakdown\secondary breakdown failures were catastrophic.
Would be simple to test for - measure between driver case(s) and pin B Solenoid Drive.
Driver cases should be shorted together, and to Pin B - any resistance would indicate the problem may have started there.
Measure between cases and pin D +12v power - that is the Collector-Emitter junction, which should essentially measure as open in a functional transistor. Shorted is dead.
If Driver case-to-case measures any resistance above zero, the electrical connection thru the screws is bad. It is a direct short in the module.
Continuing, these same modifications could allow for fast verification of:

blown series diode - no internal power. Resistance test for that requires getting into the pcb.
Could be logic failure - measure each connector pin to the others, none should be shorted.
or (3.)
bi-polar transistor specs deterioration. Poor thermal and or secondary breakdown susceptibility, severely mismatched hfe between parallel pairs, etc. One driver, running hotter than the other, fails, the remaining driver overheats and fails. No recovery.
in which case the unit could be given a proper burial. redface.gif

I will begin creating an approach to machining and building a reliable jig as soon as I can acquire some failed units, and will catalog and post my findings and test results for inspection.

Anyone willing to donate failed units or test repaired/upgraded ones, please email me at my address below.

jd, I am sincerely grateful, as I am sure are many others on TDP, for your efforts and vital data regarding this faulty module which has been the source of so much speculation, grief and expense. Thank you for making your observations available. Given a workable application of these over a period of time, a refinement of understanding, results & reliability might just be within our grasp.

D. ;)

[GARY PAGE]

Ok guys here is my experience. The original PSD was mounted on the FSD on the manifold, stock location. After about 10 months service truck would stall at any speed and it was getting more frequent to the point it was not safe to drive. I relocated the FSD and PSD on a remote harness behind the drivers headlight, no help. The PSD was mounted by the engine builder. I never received the instructions on the FSD and was not aware of the critical pressure issues. When I removed the original PSD the bolts were a lot looser that 23 FL LB for sure. I noted the GM heat transfer pad was used in place of the FSD heat transfer pad. I purchased a new PSD and mounted it on the FSD. When I mounted the new PSD I applied heat sink compound to the PSD only and torqued it to 23 FT LB with locktite blue since I did not have the FSD heat transfer pad. The new PSD has fixed the stalling condition. Having said all that I sure wish I had a scope to make A/B signal comparison this would shed some light on the situation, there sould be some notable difference in the signals. The PSD is under warranty so I will most likely need to return it to the Avants. I will ask Bennie if I can keep it and offer to anyone that may be able to trouble shoot and report on their findings, he may go along with that, I don

[gmctd]

First, some confusion prevails when referring to the "Module".
I think accurate reporting will require a few terminology guidelines.
To wit:

Manuals refer to the Fuel Solenoid Driver (FSD) in some areas, and to the Pump Mounted Driver (PMD) in other areas, probably as to whether it is in the hand (FSD) or actually on the engine (PMD).

Adding to that confusion, at any Service Managers meeting across America, conversation may involve "What's the BFD with this (choose one)(FSD) (PMD)? What am I supposed to tell the Customer about this POS?"
Which, of course, filters out into the Service Bay and into the Customer Base, thence onto the hiways and byways of America. :confused:

Further, the BETA FSD Cooler entered the scene, where the PMD may be removed from the pump and installed on the Cooler, where it again becomes the FSD ( 'again' because the Module had been held in the hand prior to being factory-mounted on the pump).

With so many choices, I refer to it as FSD\PMD. However, to save strokes for the neophyte 'hunt-and-peck' typist, why not just simply - FSD.

For the BETA FSD Cooler and it's many clones, why not the Cooler, captalized to prevent confusion with the '(inter)cooler".
If commercially available, specify the brand.
If it is a piece hacked out of one of the wife's frying pans, specify that also. (She doesn't read any of your posts anyway, does she?) ;)
Thermal characteristics are important.

Now, begging Gary's pardon, my interpretation is that his replacement engine arrived with the FSD installed on a Cooler which was mounted on the intake manifold.
Relocating the assembly to a cooler spot after several stall-restart failures did not cure that problem.
Further examination revealed variance in FSD-to-Cooler mounting procedure, involving the thermal transfer pad.
Recent replacement with a new FSD resolved some of his issues.
Some, because reading between the lines, he is still mad enough to "take this POS and shove it! :mad: "

See how the confusion in terminology trickles down from the Service Manager's meeting? ;)

'Atta boy, Gary.

Excellent suggestions, StephenA. When you have a defunct FSD in-hand, much more will be revealed.
Pop the plastic cover off, cut the corners of the 'walls', then peel the walls away from the heatsink.
I am looking forward to whatever we all can make of this.

Postscript: I do hope my tongue-in-cheek writing style does not offend any DP readers.
I am cognizant that this subject-matter, and it's results, could be very important to many, many 6.5 owners around the world.
I use the comic-relief to 'smooth-over' a somewhat didactic delivery in posting.
Please bear with me, and us.

tnx
jd

[StephenA]

Hi Gary,
Thanks to your original post on PSD Electrical Signals Analysis & other threads on this topic, we are on the way to a consolidation of our knowledge and resources, and a better ultimate understanding and plan of action. Continuing this process is a good idea.
If we could figure out how to get you a scope, we could take advantage of signal analysis on the actual truck and components you are familair with, as well as your 27 years of experience as an electrical engineer.
What city are you in? Perhaps there are TDP members nearby that have access to a scope? What resolution do you require? 25-30Mhz scopes were easy & cheap to rent in LA, when I used to live there -I don't know about your town. Perhaps a 70s or 80s Leader could be found on ebay for very little. As we proceed with taking measures to upgrade or repair units, you having a scope & truck to confirm results would no doubt prove invaluable, given your areas of expertise.
I will be surfing ebay to replace the scope I had stolen; I will let you know what I find, if you are interested?

Hi jd,

Excellent suggestions, StephenA. When you have a defunct FSD in-hand, much more will be revealed.
Pop the plastic cover off, cut the corners of the 'walls', then peel the walls away from the heatsink.
I am looking forward to whatever we all can make of this.
Can't wait to get my hands on one. I called one TDP member at what should have been around 9:00AM the other day & only succeeded in unintentionally disurbing him from sleeping; must've worked late. I will try again late today.

I agree with your terminology recommendations. FSD & ___ Cooler it is. We might reserve BFD for any successfully repaired or upgraded FSD's and POS for any ones we manage to make worse?

TO ALL:
PLEASE SHIP ANY & ALL FAILED FSD'S (not under warranty) TO:

Stephen Ambrose
1021 Market Plaza
Suite 121,
Pueblo West, CO 81007

Any FSD's successfully repaired or upgraded during this R&D stage will ultimately be returned free of charge for testing & use in the owner's vehicle.

If you have several, send them all, realizing it may take a bit of time & distruction to get to a workable approach. Please email me so I can keep an eye out for your packages.

I have set up my mill.

smile.gif

[ 11-02-2003, 11:13 AM: Message edited by: StephenA ]

[gmctd]

Comparing data in Gary's post and BillH's post, some additional information is important.

If the FSD is mounted to a Cooler, please specify
A. if an FSD extension harness is used
1. total harness extension length in inches. Need actual wiring dimension, not physical distance between Inj Pump and Cooler.
2. homebrew or commercially available
B. homebrew or commercial Cooler. Physical dimensions if homebrew.
C. actual Cooler mounting location.

To determine actual nature of all failures, stall-no restart (dead) FSD modules are also required. These can be scientifically tested for actual catastrophic failure, normal component failure, even faulty production procedures.

If some type of warranty situation exists with an in-hand failed module, please, talk it over with the supplier before sending it for testing. He may not be comfortable with product testing, informal or no.

Thanks, folks

jd

[StephenA]

ditto jd, the above post is ammended to:

TO ALL:
PLEASE SHIP ANY & ALL FAILED FSD'S (not under warranty) TO:

Stephen Ambrose
1021 Market Plaza
Suite 121,
Pueblo West, CO 81007


Please specify the conditions resulting in failure, including:


If the FSD is mounted to a Cooler, please specify
A. if an FSD extension harness is used
1. total harness extension length in inches. Need actual wiring dimension, not physical distance between Inj Pump and Cooler.
2. homebrew or commercially available
B. homebrew or commercial Cooler. Physical dimensions if homebrew.
C. actual Cooler mounting location.

To determine actual nature of all failures, stall-no restart (dead) FSD modules are also required. Any FSD's successfully repaired or upgraded during this R&D stage will ultimately be returned free of charge for testing & use in the owner's vehicle.

[GARY PAGE]

JD you are correct we need to get the terminology settled. The FSD that I referred is the FSD Cooler Heat Sink Gismo device by Beta. The PSD if the GM pump solenoid driver, which comes on, the injection pump, in my case it was remote mounted. You read between the lines and got it right! My location is Murfreesboro, TN if someone has some test equipment and wants to get with me to test the devices.

[GARY PAGE]

30 Amps wow! The wire between the pumpand the PSD is way to small for the job in my opinion and goes way back to my early posts concerning PSD extension wiring design considerations. There is most certainly a significant drop in wiring and connectors. If the failure or shall we say transistor degradation is in the PSD outputs, not a hard failure, then how about taking the output of the from the PSD to the pump solenoid output and letting it drive an after market driver pair. The driver pair could be designed more robust without all the the other stuff hopefully reducing the replacement cost and improving the PSD reliability by allowing to drive a lighter load and maybe larger AWG wire to the selonid would be a bad idea as well

[Bill H]

Damn !!! picky picky picky on the acronyms !!! But just to prove I'm not above conforming to the newly adopted convention, here's my original post from another thread, with all the PMD, FSD, BFD & POS 3-letter words just the way you picky SOB's want em. I've also added some details about my homebrew cooler and cable.

""Here's some more food for thought that might inspire some clever dude to dig a little deeper into why the PMD design is such a POS. The PMD mounted on the IP failed, to the point that it would allow a cold start every time, but after idling for 5 minutes the engine would stall, every time. I unplugged the connector to the PMD and plugged it into another FSD (call it X1) mounted on a homemade cooler (1/4" aluminum bar 3"x12" with 6 alum fins 3"x2" screwed onto the bar) using the threaded holes on the intake manifold where the plastic "TurboPower" POS used to mount. X1 cured the stalling problem, but it was a loaner from a friend, so I bought 2 more FSD's, one to run and one to carry as a spare, (call them X2 and X3).

I then made an extension cable (14 gage stranded thhn wire 5'long) to mount X2 behind the driver's side battery to keep it farther away from the engine heat. This worked fine for a few days, but one morning, no start. Switched back to X1 and still no start. Switched to X3 and VROOM !!! I couldn't believe X1 and X2 had failed, so I plugged them in again. Same story, X1 and X2 no start. Replaced X3 and VROOM !!! Still skeptical about X1 and X2 being bad, I removed the extension cable. Without the cable, all three worked fine! The point being that the connection/wiring to the FSD is so critical that if not just right, 2 good ones won't work while a third will work. How many good FSD's might have been replaced, when actually the connector or extension cable or wiring may have been at fault? Does anyone have a bad FSD they want to donate to me so I can cut off the connector to make a better extension cable? A friend had success making his extension cable using the connector cut from his bad FSD. I used .050" dia brass nails for the pins on my homebrew cable (didn't prove to work too well).

I also wonder how the OEM PMD harness wires (16 or 18 gage?) can carry enough current to make the PMD/FSD get as hot as it does. Could one problem be that the wires aren't heavy enough? Could a little bit of extra resistance in the connector or wiring (from heat or corrosion or a slightly loose connection) cause the PMD/FSD to overheat and fail?

One last observation, the screws on the FSD attaching it to my homebrew cooler were nice and tight when I mounted it last Wednesday. When I checked the screws today, 4 days and 200 miles later, all 4 needed about 1 full turn to get them as tight as they were last Wednesday. Hence I invested $5 on loctite blue at Ace hardware today.

[StephenA]

The wiring harness & switching for the headlights is too light. The OPS was revised because it couldn't carry the current to the lift pump. The resistor in the instrument panel dimmer burns out from heat. The ignition switch often fails, the windshield wiper solder joints fail, etc., etc. Seems like with all of these systems being under engineered, it wouldn't be a surprise to find that the harness for the FSD wasn't up to the job.
Is clipping through lack of current a possible factor here? What's the waveform like, typically -anyone know? Clipping even a square wave could be rough on the pump & solenoid.

[GARY PAGE]

After reading JD's write up I am convinced there is hope. I will be working on a design and will publish my results in 6 weeks.

[StephenA]

That's exciting Gary!

[gmctd]

Excellent, BillH! I don't remember specifying that SOB designator, but it works. ;)

By the way, I wasn't ignoring your post.
Wiring harness extension questions have popped up every so often, here, but no definite, repeatable data, pro or con, has been correlated to FSD failure. But, because several DP Advertisers offer extended harnesses, it can open a big can of worms.

I personally have no pro or con data on the Cooler or the harness extension.

Reservations concerning extended wire length and spurious triggering prompted mounting my replacement back on the Inj Pump, with no repeat failure in two years. Cooling system modifications have since kept the temperature gage below 200deg, with one towing run up to 210deg, but usually at 180.

Someone posted where Bill Heath, of Heath Diesel, verified his extended harness mounting has made 200,000 miles with no failure.

You are correct - sound wiring practice regarding wire ampacity and termination are extremely important, here.
Maybe these tests will offer some pertinent data, with you folks help.

jd

[StephenA]

Seems to me that an important step in all of this is to be able to duplicate the various degrees and symptoms of failure at will. So far, I have no takers on my invitation for failed FSDs that I am aware of. But once and if they start arriving, it would be helpful after successfully repairing one, to deliberatly loosen the screws, under power it, over heat it, spike it, etc. etc. Only problem for me is my truck is a 92 (not that I mind the lack of problems). I will need to find 94 or later 6.5 in my area. Anyone know of any TDP members in Colorado?

[StephenA]

BTW jd- regarding the time stamp on your messages, I believe there is an offset adjustment for your time zone under the "My Profile" links.
Thanks again for all the fine data.

[turbovair]

StevenA,
I got your information on where to mail the failed FSD.Unfortunately, I dont have one to mail you.My truck is running fine right now.Will keep you in mind.

[gmctd]

Thanks, Stephen - found it, fixed it.
I've said it before, and I'll say it again - I am an internet illiterate. smile.gif

jd

[S\W Off Road]

Stephen, You will be receiving a failed PMD/FSD from me soon.

Thanks, Mike

[ucdavis]

FWIW, this POSt has been the BESt on TDP since I JOI-NED.
Coupla more suggested conventions:
1) Stanadyne monogram = FSD top
2) FSD connector = FSD front
3) FSD screws = torx mounting screws
4) SS screws = those holding transistors to FSD heatsink base
5) PCB = printed sircuit board
IIRC, the SS screws mount up from the bottm, w/the kep nuts on top of the PC board inside. What I don't recall for sure is whether the kep nuts are engulfed in potting on top of the PCB. If yes, they should be sufficiently "kept" to allow tightening of the SS screws up to reasonable limits to insure performance according to design; if not held in potting, turning the screws might create some physical interference w/in the PCB neighborhood by a potentially-rotating kep nut. IOW, if kep nuts are potted to PCB, we should be able to make an inch-lb torque recommendation that could be verified B4 installation of a new FSD or for checking on a suspect unit.
Does this sound correct?
Anybody got ideas on the torque spec?

[GARY PAGE]

JD and others here is my thinking. JD failure analysis indicates a heat issue, which I assume is caused by the drivers. So I am thinking of of a solution to take the load off the drivers and let the Pump Solenoid Driver (PSD) Drive an amplifier; which in turn drives the Injection Pump Solenoid (IPS). It would seem to me that amplifier could be designed to require input drive 1/10 of the original PSD output requirement; thereby significantly reducing the power required out of this high priced module; which I don

[jeffreydmet]

As far as the screw torque specs I may be able to help. I am a Mechanical Engineer and can get my hands on the specs. What I need to know wheather their are any numbers or markings on the head of the screw. I also need to know what size it is. Is it metric or English and the thread pitch. Is it a fairly hard stainless or is it fairly easy to strip the head. What type head does it have?

[moondoggie]

Good Day!

Keep in mind, the FSD/PMD/whatever also provides an output to the vehicle's PCM, which in some way is related to the Fuel Solenoid closing, which allows the PCM to generate a codes & turn on the SES light, causing lots of folks to keep Mr. Goodwrench eating regularly (not me, to this point in time).

Blessings!

Brian Johnson, #5044

[GARY PAGE]

Good point and I asked JD just that on an online discussion, good question. The only way the PSD tell could tell from the output signal would be by analysis of the signal, I don

[StephenA]

TurboVair & S/W Off Road:
Thanks for the reply/support- will look forward to receiving & analysing your modules (Turbovair-I hope yours just keeps on running; many do!)
UCDavis: I like your additional terminology; sometimes just defining things makes for an easy solution. Anyone mind - jd, Gary?
I will know more about the SS Screws & kep nuts/potting once I receive Mike's FSD. Torq specs are a must; once I have my hands on one, I may opt to extend the bolts and torque them down directly to additional heat sink hardware, including special lock washers - don't know, too early to tell... Nitro cooling? Just kidding :D

Gary- I'm all for your mod to take the load off the drivers. I will endeavor to supply you with further hard data on what has actually been failing in the faulty modules I receive; then we can compare performance of the existing engineering and your upgrade, showing it's advantages. Don't know if you find my input helpful; but if so, I look forward to working together on this. If not, no sweat.

All: I feel like a team effort here could result in some very effective options ranging from confirming the true causation(s) of the problems on a truly representative number of faulty/failed units, to possible repairs & upgrades of recoverable or new FSD's, to realization of replacement drivers or even fully redesigned and proven modules.
I personally believe in the talent we have in our membership. What is required now is much testing and a full tally of symtoms and their causes from any/everyone who has experience with FSD's. Opinions can be helpful, but hard facts accurately observed and reported are invaluable. I realize there is much data in past threads, but as this venture develops, certain aspects will expose themselves as vital, i.e., loose screws tightened- big difference, or no difference - possible cause being other components, etc. etc. Testing. The more FSD's the better. You get the idea. Any fixes we come up with will need validation from participants in our membership and a runway period of some sort to get off the ground. Sounds like fun, especially compared to constantly repairing & possibly dumping the otherwise useful trucks many of us have grown fond of...
Just my $.02;)

[n3qik]

My 2 cents, The one I had phillips head screws thru PCB/heatsink for mounting. And ,yes the heads are part of the potting with the nuts on the transistor side of heatsink.

[tom.mcinerney]

Stephen A.: I believe that some dealers {not sure if GM or Stanadyne, or both} were confiscating and destroying old FSD/PMD/BFD units when exchanging them, or complete injection pump assemblies, on warranty.
Also, i think a number of members removed the electrical connectors for harness extensions.
I also think some dealers might be willing to cooperate with you by providing you with their exchange/confiscated FSD units.
Possibly you could write/call some dealers/truck shops who might forward the FSDs they replace?
The advertising injection pump people(Gomers/USDiesel, DSG, etc.), might be a place to start. This becomes a contact/communication challenge. We can't really hope for FSD failures...!.

[StephenA]

n3qik: so you've seen the screws too... I can't wait. Were the screws loose on the one you inspected, or torqued down to the sink?

Excellent resources, tom mac. I'll check it out & report back. I had hear of the distruction, but was hoping some dealers might have tired of the endless replacements & opt to lend us a hand.
Too true- hoping that FSD's will fail is definitely not called for here- they need all the support we can give! smile.gif

[gmctd]

Great responses - keep them coming, folks.

The screws from my FSD are 6-32x1/2, with 1/4" kep nut.
Equally important, the screws pull the transistor to the heatsink, and make electrical connection to the pcb.
There is approx .060" epoxy potting material between the heatsink and the pcb, providing a compressible cushion.
The pcb is compressible, also, but the fiberglass layers provide some restriction to 'crush'.
Thermal compression\expansion of this compound can result in reduction of as-torqued dimension.
I don't think the nut is just backing off.

Hmmm...just re-read my first post. Let me correctify that here.
The screws are inserted thru the pcb to the transistors - the kep nuts cinch against the transistor case.
The head is covered over with epoxy, but can be distinguished from other componentry.
The need for tightening (read - turning) the screw is to burnish the copper pads for improved electrical connection.
The circuit pads in my Module appeared heat-darkened\oxidized upon removing the screws.
In three pre-owned modules - '94(mine),'97,'01 (on the truck now) - the kep nuts were various stages of loose, easily finger tightened with a 3" length nut-driver.

The manual describes the FSD output drive to be current-regulated, with a signal provided to the PCM indicating solenoid is fully seated.
Meaning drive current would change rapidly at this point, where an E\I level sense circuit would set the mission accomplished flag.
I think this design would be difficult to adapt output buffers.

I also think mos-fet drivers may be problematic due to static sensitivity, requiring special handling technique. Still, that would be my first choice.

Again, thanks, folks.
And, please - prove me wrong.

jd

[Bill H]

I called Midwest Fuel Injection (MFI) where I bought my 2 new FSD's ($190 + $7.50 shipping each) and Brian there said he would try to send me a used FSD that I could cut up to make an extension cable. I asked if there was any kind of warrentee on the 2 FSD's I bought. He said Stanadyne just issued a policy memo last month that there was, if the Stanadyne authorized shop installed it on the IP, otherwise not. MFI also sells and installs FSD coolers, claiming the cooler mount to be superior to mounting on the IP, so Brian was going to get clarification on the warrentee policy.

GM warrentee directs the shop to destroy the removed FSD with a hammer. Stanadyne appearantly isn't quite so vindictive.

I told Brian (at MFI) that TDP was making a project of reengineering the FSD mal-f*ck-tion and asked if they had a cache of used ones they could send us for diabolical experiments. He said he'd look into it and let me know.

One last thought, the new FSD's come with a sticker showing they've been tested. Would it help if we knew what test the new units must pass at Stanadyne? I called Stanadyne earlier about finding a connector to make an extension cable and they were NOOOOOOOOOOOO help. Wonder why? heheh

[gmctd]

Good work, Bill. I would try the two that failed with your reworked harness. Make sure the nuts are cinched down on the drivers, first. If either still fails, I would be personally interested in taking a look at it. I've everything set to fab two harnesses and a Cooler specifically as a test bed for just such pieces.

jd

[ucdavis]

Jeffrey,
That's 6-32 x 1/2" w/ 1/4" hex kep nut.
The phillips head is up, kep nut down. You can view the hex nuts (& transistors) by removing the diamond shaped black plastic cover(s) on the bottom of the FSD. Assembly goes (top to bottom, & correct me where I err:
1) Stanadyne monogram plastic lid on FSD,
2) potting material
3) screw head,
4) PCB
5) More potting mat'l? I wasn't clear on that.
6) FSD heatsink base shoulder that receives screw shank
7) transistor sheet metal case
8) kep nut
9) black plastic diamond shaped transistor cover
10) air (in diamond shaped cut-out in FSD heatsink)
Re: hardness, I could cut a slice into the phillips round head w/hacksaw blade, but it was tough. That's as close as I can get you on that. I'm thinking the PCB would crack way before the torque spec for full tension on the screw material was reached or any limit was reached on the heatsink material (which, I believe is made from grade #1 melted-down Buick carburetors for q.c. purposes), so that compression on the PCB would control if the potting would hold the head without slipping. I'd use the under-head area exclusive of pilot hole in PCB as bearing on PCB for area, and multiply that by the allowable compressive stress (acs) for the PCB to give allowable pressure in lbs. I'd judge acs for PCB @ ~ equiv. or maybe a bit less to structural fiberglass which has an ultimate of 15,000 perp to fibers. Mahinery's (M's) lists safety factor for engineered plastics @ ~ 10 where failure would be critical, which I would say it is here (crushing the PCB would be N.G.), so that's about 1,500 psi on the high end. 1/4" kep nut area > 6x32 round head area so screw head area controls.
M's lists round head diameter of 6x32 @ .25". I couldn't find a spec for clearance hole for the PCB, but M's lists standard-fit for metric sizes @ 10% above nominal shank diameter (.138 per M's), so that would be .138 + .014 = .152 ID, and .25 OD, & area under head would be .0309 sq.in.
Using that area x 1500 psi = 46# compression on the high end.
I didn't make any analysis of differential coefficients of thermal expansion, or the effect of cyclical expansion/contraction. I'd guess the assembly has a min life-cycle potential of zero, farenheit, and max of about 240 deg. on the IP though hopefully less, and zero/140 on a good cooler (avoidance of high heat may be as attractive in the final analysis as avoidance of high cyclical swings?).
Check & correct my assumptions & math, then give us your additional commentary & a guess @ torque spec to achieve the desired clamping force. This is on the dull end of the science around this post, but its the one thing a dummy like me can get done (i.e. torque a threaded gizmo).
Off screw topic- I believe the FSD harness wire is 18ga, teflon insulated (high temp resistant), and I know it is tinned.
Thanks.

[Turbine Doc]

Okay just looked at my new in box spare, Stanadyne PN 34583, nuts/washer/studs can only be seen if plastic transistor covers are off no phillips head or torx exposed, what is exposed then are 2 transistors and 2 nuts & star lockwashers for each transistor, plastic covers are marked Thermalloy 8909NB Markings on actual transistor letters ON in a circle, then MJ15004 MEXICO BM0108

[n3qik]

Stephen Ambrose

Nuts where tight, and no marks under screw heads at PC.

Note: I got the FSD with a IP off eBay, so it may have been good.


To all,

What is the resistance value of a #9 resistor?

[GARY PAGE]

JD if you are saying the driver requires 30 Amps then the transistor indicated in an early post diesn't have the Ic to support. Below is a data sheet indicateing 20 Amps max! This is an old part! ECG61 and 2N6021 are the equivlents.

Military/High-Rel No
V(BR)CEO (V) 140ц
V(BR)CBO (V) 140
I(C) Max. (A) 20
Absolute Max. Power Diss. (W) 250
Maximum Operating Temp (шC) 175х
I(CBO) Max. (A) 100uч
@V(CBO) (V) (Test Condition)
V(CE)sat Max. (V)
@I(C) (A) (Test Condition)
@I(B) (A) (Test Condition)
h(FE) Min. Current gain. 25
h(FE) Max. Current gain. 150
@I(C) (A) (Test Condition) 5.0
@V(CE) (V) (Test Condition) 2.0
f(T) Min. (Hz) Transition Freq 2.0M
@I(C) (A) (Test Condition)
@V(CE) (V) (Test Condition)
t(d) Max. (s) Delay time.
t(r) Max. (s) Rise time
t(on) Max. (s) On time.
t(s) Max. (s) Storage time.
t(f) Max. (s) Fall time.
t(off) Max. (s) Off time
Package Style TO-3
Mounting Style T
Pinout Equivalence Code 3-4
Description


--------------------------------------------------------------------------------

[GARY PAGE]

OK here is anoher idea. The link
http://noel.feld.cvut.cz/semi/motorola/books/sg73/pdf/5_5bipolar_msg.pdf

Look for the 15004 part as the one we currently hace in the FSD

It Has the transistors specs of the 15004 reported above. We selected a beefer part and installed it in a failed FSD and see what happens???

[gmctd]

Gary, I had just logged on to ask if your recent failure had loosened driver fasteners. I think yours is the most recent.
Have you checked, or are you leaving it as-is for monitoring with a scope?

You are correct - the MJ15004 is a 140 volt 20 amp PNP device, but the driver pair is parallel connected for enhanced current drive. May be some redundancy - that 20amps is continuous collector current.
Properly heat-sinked, it can be overdriven in pulsed mode. Off-time allows cooling, right?

I don't think increasing the electrical size, amps\volts, is the answer, Gary.
I really believe the answer is partly in mounting and fastening, partly in bi-polar device specs being below-standard.
I'm sure what resolved the failures for my company would do the same here.

A Forum can be an excellent tool for providing viable alternate answers.

While a relatively old device, the 15004 was the device of choice in '94, '97, and '01. Havent seen a Module later than '01 - I would suspect they are still in use.

It is easy to check - just pop the plastic cover off both devices and note the oem, device number, date code, and origin of manufacture.

That date code will also tell approximate date of FSD manufacture.

Good responses, all.

jd

[ 11-04-2003, 05:35 PM: Message edited by: gmctd ]

[GARY PAGE]

No JD I have not since mine is a warranty return; but I intend to speak with Avants tomorrow and if they way see their way clear for some experimentation this could be good business for all of us. Yes the device will cool when off. I am not real sure exactly what goes on but my calculation go something like a peak switching time if red line is (3800/4)8 or 15.2 Khz so it in a non saturated sate much of the time. There were several devices in the list that could be substituted that have heaver IC and a bit more PD up to 300 watts. We should keep hFe same of better, that

[gmctd]

The drivers running loose-mounted would
reduce thermal transfer into the heat-sink, while at the same time creating thermal increase due to poor collector\pcb connection.
As you know, device power handling ability is limited by two factors - average junction temperature and secondary breakdown.
Increasing case temp derates the power capability to below that of second breakdown limitations, which also then derates second breakdown susceptibility from reverse emf from the solenoid.
I would sincerely suspect this would affect the pre-driver also in a darlington configuration where the predriver has lower collector\emitter rating Vceo.

I would think, also, most of the stall-restart faiures never got to that stage, as the driver would have had the vehicle repaired soon after failure started.

I'm fairly certain my falure was at the limit, because the insulating washers were 'laminated' to the driver cases, indicating H-O-T.

Thanks

[kowsoc]

I don't believe it is the power transistors that always fail here even though they create all the heat. When my FSD went south I carefully jumpered in two new transistors I picked up cheap ($6 each) at an industrial electronics warehouse. The truck did not start. Plugged in my new FSD and truck fired right up. There's something else going on deep in the epoxy.

The transistors have to carry a heavy current (30 A) but only intermittently. I believe I heard 50 watts somewhere? That's easier to believe. Something harder to believe is the tiny circuitry inside those power transistors stands up as well as it does....I removed the metal covers on them and the semiconductor inside is only about 1/8" square :eek:

I wish you guys all the luck.....but for now my spare doesn't take up much glove box space. :D

[gmctd]

You are right, kowsoc - you should see what that 1/8" little square did to the thermally conductive insulator pads on my drivers.

There are also normal-type failures in these, where a chip gives up the ghost, or resistor burns open, or a cap shorts, bad solder-flowed connections, poor etch - not much can be done about those, but I am very interested in how many failed from loose screws and such.

Problem will be, most folks did not hang on to the failed Modules, and only have bad experiences to report.

Mine was intermittent, and I wish I'd had the intestinal fortitude to re-install the thing as a test. Would have if I'd put in a remote Cooler, but it was entirely too much trouble to remove the intake and dual tstat housing to pull it off the IP again.
Anyway, I was dying to see what was inside - always been a 'failing' of mine. Gots to see what's inside, how does it work.

Keep posting

[Cowracer]

Heres a thought. How hard would it be to build a test rig for these. You could generate the low power logic signals, and have the output circut drive a dummy load.

That way, you could test intermittant FSD's to failure, then examine the failure mode, without getting stuck in the boonies.

You could also possibly simulate temp failures by simply baking the unit in a warm oven.

I am more of an electical and automation engineer, that electronics, but it seems that we are on the right track here!

Tim

[gmctd]

Tim, I've been detailing that idea since I first posted this 2 years or so ago, but using the actual PCM and emulating control feedback signals.
Got the PCM, harness, FSD, generators, etc.
Figgered I'd do that after I retire, shortly.

Should be able to do it otherwise, but I'm not at ease standing on a ladder and hanging over a tall fender while scoping signals out, long term.

Keep posting.

[More Power]

Some questions and observations.....

Is the FSD patented by Stanadyne?

If so, what impact would that have on a vendor offering an aftermarket FSD?

Because some here have pushed lawsuits and NHTSA lists, what impact would these have on a small aftermaket vendor offering replacement FSD modules? Don't get me wrong, I think a replacement that promises improved reliability is a good thing, and am encouraging that endeavour.

I heard a few years ago that some FSD failures were the result of circuit board cracking due to improper mounting screw torque. Those of you who have seen the insides, is this an issue?

I've thought of using a 7-8mm bottoming drill bit to remove all of the plastic down to the alum base, then use four stiff coil springs under the mounting screws. The springs should help maintain the clamping load over a longer period of time.

MP

[Cowracer]

JD,

But rather than use an actual PCM I was thinking that you could make a variable signal generator where you could control pulse frequency and duration, and vary the load impedance as well.

Maybe overdriving the FSD would reveal things that would otherwise go unnoticed. Maybe there is an odd harmonic that changes wave shape. (bear in mind that I am on the slippery edge of my electronics knowledge. If these things were controlled by and A-B SLC 5/05, I'd be right up in there!).

MP-I thought of the spring thing myself, but if you have yours mounted on a heatsink style cooler, why not just use a plate of metal and some hefty screws to clamp the FSD to the heatsink.

Take some 1/8' steel about 1.5" wider on all sides than the FSD, drill suitable holes on the corners, and corresponding holes in the heatsink. If you sandwich the FSD between the heatsink and the plate, you can get the FSD as tight to the heatsink as you want without worrying about cracking the boards. This setup should also be less suspectable to loosening up than those puny stock screws.

Tim

[gmctd]

MP I would think the module would need be exact circuitry duplicate to incur legal hassle, no matter what the enclosure.
Signature analysis could be used to determine that.
Functional duplication may be an arguable issue.
Offering an 'improved' version of the Stanadyne piece could create warranty problems for vendor and oem, based on my employer's experience.
But, also might relieve some pressure from S.

OEM (not Stanadyne) copyright notice on my '94 series pcb is '88 - '92.
I have later modules, to '01, pre-owned but presumed functional, that I have not wanted to disturb beyond addressing the mechanical\electrical fastener interface.
Our notice is updated every few years.

The pcb corners are notched deeply, as if to prevent over-torque stress. Dimensions are essentially identical to the plastic Stanadyne cover.
Based on my findings, the potting compounds beneath the screw head could be compressed considerably without effecting the pcb, using oem Torx fasteners.
I drilled out the excess epoxy when installing the replacement FSD, much as you are suggesting, using insulating washers.

Far as testing, signals would require much observation with a scope and a Tech-II, to duplicate the engine bay electronic environment in a test set.
A Basic Stamp could be used to generate normal and stressed signals, but I am software illiterate, so that's right out.
Also, my scope appears to work longer and better on my workbench, with me sitting down in front of it, if you get my drift ;) .

And that's why I posted this on three separate occasions - to give you smarter, younger guys a shot at it.
I'm still working on it, just slowly. Things will come together when I get a Tech-II.
Thanks

[m-keith]

I have only one thing to say about all this....Huh? :confused: :D

Seriously, I'm glad ya'll are tackling this issue. I'm about as dumb as a brick when it comes to electronics, but I'm glad to help out any way I can. I'm in the Houston area, & I'm happy to serve as unskilled helper, crash test dummy, cheerleader...whatever.

When I get around to replacing my intake manifold gaskets, I'll be sure to get my failed PMD off the side of the pump & send it to whoever. My new one is mounted on a remote heat sync bolted to the intake (for now). If there's any testing I can help out with, feel free to contact me. Also, I'm going to buy some new injectors from a local diesel shop in the near future. I'll be sure to ask about any failed PMD's lyning around.

[GARY PAGE]

Huh all good ideas, here

[gmctd]

Good thinking, Gary. More will be revealed to you when you get a chance to in-depth examine a module.
Having yours remote mounted affords you a good test bed.

How did yours fail, M-Kieth? You might want to post that in the FSD Failure post by TBOGEMIREP.
Or did I just miss it?

Good posts, folks - keep them coming.
All is appreciated.

[GARY PAGE]

Jim on you post concerning liability you are correct. This thought crossed my mine as well. In today

[tom.mcinerney]

I like this thread.
Gary--one of the DTC 'codes' that set is something like 'pulse width too long', that is, the solenoid didn't seat(rise?) in specified interval. I think the PCM might dictate 'limp-home-mode' if it sees that. UCalDavis or JohnKennedy can answer. If the initial iteration causes limp home, will it be possible to shape the output of the OEM FSD when coupled to the 'secondary GP Amp' such that after an interval of, say 1.8 ms, it reflects coupling to a seated(or is that a lifted) fuel solenoid? Maybe a timer to an inductive short? OK, waveforms. I've got an old Tx 545B and 585A, but stored outside temps YEARS they won't work, would only add to probs!
More Power- Belleville spring disc/washers might be able to maintain the mounting tension, if there's room for them...both at transistor mounts and FSD mtg. [They'd be nice for intake man bolts too, but not enough space on flanges].

[ 11-05-2003, 08:43 PM: Message edited by: tom mac 95 ]

[m-keith]

You might want to post that in the FSD Failure post by TBOGEMIREP.
Will do.

[gmctd]

tom mac, if you'll pop the covers off those scopes and replace all the electrolytics, including the small one up towards the front, botttom side of the pca, they will probably recover nicely.
The elecrtolyte dries in all electrolytic types - those scopes have been around since the '70s - '80s.

[Dimsdale]

I have to wonder if Gary isn't on to something with the wire gauge issue in the wiring harness.

Didn't Stanadyne and/or GM start selling the FSD and a new harness as a package (though still available individually from GM Parts Direct)?

Has anyone examined one of the new harnesses?

[gmctd]

I think warranty considerations played more of a part in that because of defective or corroded original harness failures with replacement FSD.
An oil soaked and\or heat hardened harness does not make good connections.
Some of the later IP harnesses I've seen had defective terminal crimp at the solenoid end, easier noticeble than in the connector end.
May want to check the new harness for increased diameter of the solenoid wires, red and black.
Black wire ties the solenoid and FSD to engine ground via screw on the inj pump.
Red is Solenoid Drive.
No point in increasing +12v supply wire diameter to greater size than the engine harness wire, right?
Same with PCM drive wire, and remaining wire is signal only.

So, if anyone can check it out, please post variances, as dimsdale is suggesting.

[StephenA]

Keeping up with all of this; will post when I have received FSD from Mike & had a chance to look at it.

[jonflies]

I read the last couple of posts and it reminded me of a similar problem I had with my Plymouth Van. The MAP sensor connector was bad and none of the dealers could find it. The intermittent connections were enough for the CPU to shut the truck down an any speeds, similar to what we're experiencing with the 6.5. Even after I pointed out that the connector could be bad (a long story how I found the issue) it took more hunting to find a dealer with a "master connector kit" with the parts necessary to rebuild it. One thing I learned from that was the use of a "co pilot" data storage unit. The unit connected between the van's CPU and it's connector, and stored 15-second time slice of data, after the driver pressed a button during an anomoly.

Could the bad connections be part of the issue?

[tom.mcinerney]

gmctd-thanks for suggestion, it's on my chore list!

[GARY PAGE]

GMCTD can you shed a little light on the mechanical properties of the Injection Pump Solenoid itself. How is the closure signal sensed? That signal being to long is what causes the DTC36 on OBDI, right. Is a OBDI DTC 35 injection pluse to short mean the selonid did not return to the rest position theryby shorting the stroke? What would make the solenoid mechanically (sticky) hard to drive and how would you correct that? What

[jeffreydmet]

UCDAVIS

I've got some numbers on the screw. Most screws appear to be made out of a stainless with 75000 psi tensile strength. Some are higher but lets use this number. At 60% of the rated tensile strength the screw is capable of 395lbs of tension wich is acheived at 12.5 in*lbs.

I agree with you in that this is too much for the PCB and the potting material under it.

I agree with most of your numbers but think that a saftey factor of 10:1 is higher than necessary. Most materials have a somewhat higher compressive strength than tensile and they are not as likely to fail in fatigue.

I did some thermal expansion estimates. I don't have good numbers on the exact materials and thicknesses being compressed by the screw but I did make some estimates based on other similar materials. Plastics typical expand something like 5-10 times faster than steel. What this does with my estimates is increase the compresive stress 3600 psi at max temps. 1500 psi at room temp would be necessary just to make sure the screw would not be loose at 0 deg F.

Because of the severe thermal cycles I would recommend tightening the screw initially to 3000 psi which is 92 lbs of tension or 3 in*lbs of torque. With that initial tension I have estimated at 240 deg F the compressive stress to be 6600psi.

This may be of concern not because of fracture but because of creep in the plastic. Plastic is noted for this problem but the glass helps. I do not think this is good design if the ground is contingent on the screw staying tight. You have indicated that it in fact doesn't. I suspect the loosening is due to plastic creep. It would be good if their were an external ground wire that doesn't depend on the tension of the screw.

[GARY PAGE]

I should be receiving 3-failed FSDs for investigation from the Avants shortly. I will try and figure out where I can store pictures for your observation and comments. You will see what I see. I need to send my intermittent unit back for warranty purposes. This is a neat thread, let

[gmctd]

The Fuel Solenoid armature travel is .005" to seat the poppet valve.

The solenoid is current driven - seating can be determined by E\I sensing circuitry for change in current drain.

DTC 36\1217 Response Time Long caused by weak solenoid (failing), dragging armature (dirty fuel residue, wear, etc), increased resistance from loose drivers, corroded\poor connections, damaged harness wiring, etc.

DTC 35\P1216 Response Time Too Short is usualy resulted from poor fuel supply, where IP pumps bubbles and solenoid seats ahead of time.

Damaged harness wiring can be where intake manifold is dropped on harness, pinching wiring to near separation, which results in poor current supply to FSD\solenoid. Many other scenarios also exist for this type failure.

Could be many reasons for GM supplying new harness with FSD - judging from what I've seen in boneyards, deteriorated original equip wiring is prime causative.

Fuel Solenoid Drivers exist in three different versions
30214 - '94-'97
34264 - '97-'98
34583 - '99-'01 <

34583 contains all improvements and enhancements resulting from on-going failure, and was supplied with new IPs, all Stanadyne rebuilds, and as replacement units.

I don't think pcb damage from the oem FSD mounting screws is possible. The IP housing is soft aluminum,the screws are grade 8, and the pcb corner edge-to-screw dimension is too great.
Murphy's law, of course, takes precedence.

Keep posting, folks - you all add to the knowledge base.

[gmctd]

jeffreydmet You are correct - separate electrical connection would help.
Also, a shoulder-screw or a spacer collar would prevent crush while maintaining electrical and thermal contact, with the fastener being bradded and soldered to the pcb.
A stainless nut would prevent chemical interaction with the transistor stainless case, while the collar would provide electrical contact.

I have the latest FSD (functional), but would not at this point be willing to sacrifice it to further the investigation.
A bird in hand, as it were.

[m-keith]

gmctd- Would these be of any use to you?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2441549486&category=33553&rd=1

If the price stays near where it is, I was thinking about snagging them for their failed PMD's. Since I'm in the Houston area, I was thinking that I could just hand 'em over to you, but I wanted to check with you first to make sure you could put them to use.

[gmctd]

That would be a hard call, Michael.
As honest opinion - one on right looks like it's been rode hard and put up wet, but one on left looks much better.
Harness appearance is of type that would cause failure with new FSD.
But, at that price, might be worth it to save core charges on a spare rebuild, if GM does supply new harness with new FSD.

I would like to disect a '99-up FSD #34583 to determine internal upgrades over FSD I investigated - same series model as those - #30214.

If you choose to get the pumps, I will look at the modules.

Thanks for your interest.

[Randee of the Redwoods]

gmctd-since you are THE man, I am buying you pumps. That's right-complete pumps. I just confirmed the purchase of one off Ebay now for less than $100 comeing from Canada. It's a blue label pump(so I want it back) and the description said it came from a running engine that began to run rough so the pump was replaced. Here's what I'd like you to do:
Since you are beginning to identify a possible pattern of symptoms(loose screws, etc), I am going to send you COMPLETE pumps with FSD still atached. If I can get the failure code, I'll send that, too. Since you are looking into the current state of the fsd as it was attached, I would like you to document the removal of the fsd; things like loose screws, burned out transisters, cracked pcb, etc. As you do this for each one(yes, it's a lot of work but it will be worth it), a good knowledge base will begin to form on 'stated failure vs. current condition/mounting of fsd'. This will help you take into account at least part of the fsd's environment while working on what caused the failure. I've decided that a "bad" fsd for testing will not tell much as you have no idea if it was mounted correctly or incorrectly to begin with(here we are back to the loose screws idea).
Drop me some input on this if you will. Email me your shipping address to forcedinductionforever at yahoo dot com. We'll go from there.
PS-I will need this blue label pump returned once you remove the possible bad fsd. Since it's the later blue label, I may use it for a rebuild for my truck. I may need a pump eventually.

[GARY PAGE]

GMCTD thanks for the info that helps. Does Standyne publish a manual on their DS4 pump? I sure would like to have one.

[gmctd]

Randee Might I offer an alternative, based on non-posted findings.

After my failure in ought one I purchased four DS-4 IPs, 1@'97 and 3@'01s, all warranty failures from same GM dealer.
One '01, new in box, never on any vehicle (except parcel delivery truck), had been dropped in shipping, breaking the driver side mounting ear, across the bolt hole, off the flange.
The broken ear piece was still in the box.
Mounting flange is triangular, one ear at top, one lower ear on either side.
The flange is still functional, but would not play in a warranty situation.
New pump\FSD\harness, broke, scrap. Serendipitous find!
Second '01 pump, pre-owned, very few miles, not even dusty, same story only passenger side ear, probably dropped in Service Bay.

Other two pumps were clean (not cleaned), and were also well worth the $75 each price.

With that experience, I would feel more comfortable if you would send only the FSD and IP harness for evluation.
You can verify IP mounting screw torque using your fingers only, no handle, on the shank of the TORX bit. If you can finger-rotate the TORX in any screw, it is un-torqued.

I appreciate your confidence, Randee.
A remote mounted FSD and Cooler might boost your confidence in your truck, as switching Modules will then be easier than changing a taillite bulb.

[MEDiesel]

Has anyone looked at the cooler on ebay for sale ,made by a guy from Buffalo,NY? What do you think? Looks interesting,comes with module,#9 calibration,just plug + play.

[Randee of the Redwoods]

gmctd-ok, I'll do that. I need the pump anyway so the purchase was not for nothing. I will document the fsd and harness and send them to you. You can mail your shipping address to the email address I gave you earlier.
As for the module now, I'm not messing with it just yet. Currently, my truck is my daily driver with zero complaints and I'm gonna ride that one until anything unfortunate happens(read: fsd failure). As much as I like to fiddle and fart around with things, "if it ain't broke,......." applies here.

[gmctd]

Good deal, Randee.

If it's oily\grimy, do not clean it - that may be part of the failure.
Enclose it in a freezer-type ziploc bag to preserve the 'ambience'.

Also, most people, especially postmen, do not like the odor of baked Diesel fuel and grime. ;)

I'll e-mail you shortly.


MEDiesel I have not seen it, but if you have not already done so, you might compare that price with gmpartsdirect.com and\or DP advertisers for value.

[More Power]

Regarding an aftermarket FSD replacement.... BETA had developed a replacment FSD quite a while ago, using aerospace components and many other engineering design considerations that address the thermo/mechanical/electrical deficiencies of the original. Durability/stress tests had proven the design changes.

I should know is a couple of weeks what/where the marketing situation is. This could/should be "the" solution.

MP

[gmctd]

I had sorta read that "between the lines" in your non-posting and previous post, Chief. Oops! redface.gif

Sorry, Beta.

It is good news.

[ 11-10-2003, 09:22 AM: Message edited by: gmctd ]

[ucdavis]

Jeffrey- 3 inch-pounds sounds like a good place to start w/an engineered guess for kep nut torque. I'd add blue loc-tite as a good keeper for this process.

Gary, Stephen, & gmtd- I have a used fuel solenoid that appears in excellent shape I can donate to the cause; not sure who can make the best use of it. I believe it is a mid-99 build date on the IP, but I still have the IP carcass & can get exact date. I scavenged some spare parts off the pump, & could also send the core (minus the FSO, timing stepper, inlet ass'bly & top plate/optical sensor). Let me know where to send either/both.
Mike@Fleming.cc

[m-keith]

MEDiesel- I bought mine from that guy on ebay (Kennedy was out of stock). So far, so good, but I've only had it a couple of weeks. It came with the resistor already in place & the FSD mounted to the cooler. Only thing I didn't like is that it doesn't come with an extension harness, but I can add that later.

The seller gives good service & prompt shipping. I found him easy to work with. I wanted a #5 resistor instead of the #9, & he was able to do that with no problem.

[More Power]

gmctd,

If anyone wants to design their own, I'd say go for it. Ingenuity and creativity are good things.

After a long phone discussion with BETA, I learned that there are several aspects of FSD design that haven't been discussed here, yet would have a significant effect on longterm durability/reliability. They've addressed all of them.

On another subject... How about aluminum cyl heads for the 6.5? I know of two sets that have been in service for about two years.

MP

[GARY PAGE]

Yes, if Beta solves the problem that

[gmctd]

UCDavis Thanks for the offer - I already have several IPs.

Stephen?
Gary?

[GARY PAGE]

I could use a junk IP if you want to donate. I would be more that welcome to receive, disassemble and publish pictures for public viewing. The major obstacle is getting a service manual that details the IP theory and servicing procedures. Even after someone corrects the FSD you can expect to have mechanical or electrical problems with the IP itself, so you only have

[rjschoolcraft]

Gary,

Here is a link to some instructions on the 6.5 electronic pump (http://www.geocities.com/MotorCity/Show/3753/6_5_litre.htm) that I found some time ago. See if this gives you any useful information.

[gmctd]

Was also an article here on the DP covering DS-4 internals and Stanadyne factory upgrades, from Gomer's Diesel, a Stanadyne Factory Service
Center.

[S\W Off Road]

Good news! I torqued the transister nuts with my Snap-on in/lbs wrench, the one that has a dial indicator, to about 5in/lbs and remounded the FSD. I am not having any more problems smile.gif I only have about 15 miles on it so lets see if that helps. The nuts were less then 1 in/lbs when I tightened them.

[gmctd]

Very good news, S\W. Did mine in ought one, and it's still running two years later, on the inj pump, with a pre-owned (used), re-torqued FSD.

Good luck with yours.

[kowsoc]

Could the cure be that simple? smile.gif

[gmctd]

Could be.
I had posted those results Fall-Winter '01 after the failure, Fall-Winter '02, and Fall-Winter '03.
Each time after surviving a blistering Texas Summer requiring constant a\c, with one towing trip per summer.
I installed a used 34583 FSD with re-torqued transistors, a used pad, and packed the cavity with silicon thermal compound.

I now think that particular 'white' compound was not a good idea, as the heat bakes the oil "carrier" out, leaving only the solids. Better compounds are available but the jury is still out on 'to use, or not to use'.

Re-torqueing is worth a try, if an FSD Cooler is being or has been installed.

If anyone re-torques and reinstalls, please report findings here or in Tim's PMD/FSD/POS Failure post, as well as successfull recovery or recurring failure.

[ 11-12-2003, 03:49 AM: Message edited by: gmctd ]

[BETA]

I have checked a number of used(defect) and new FSDs - all mounting nuts where loos.

Three "defect" units have been re-torqued, and are working fine again :D .

Instead of using a torque-wrench, I have tried 45 degrees after finger tight, which seems to work fine so far.

It's important to use a new HTP when re-installing.

How many FSDs have been replaced when they only needed some service?

[GMCfourX4]

I have a "bad" FSD on a BETA cooler which may have the same problem. When it died on me, it would start after a long cool-down, and then only run for about a minute or two, so mine may be too far gone, but I'll give it a shot tonight and post results.

-Chris

[tom.mcinerney]

Are the transistor mounting nuts accessible from the bottom [heatsink-mounting side] or top? Does one scrape/peel off top, then snug?

[ucdavis]

FYI- BillH reported the following after removing the black plastic caps from back of 2 FSDs:
One had the usual 2 kep nuts/transistor, other one had one kep nut/transistor and one standard nut per transistor.

[S\W Off Road]

Do the black plastic caps covering the transistor's back do anything other then help trap heat? Its not like the transisters are exposed and could be damaged. I would think that removing them would help more then when we remove the "Turbo Power" engine cover to help disapate heat. Anyone?

[StephenA]

gmctd, you wrote:

UCDavis Thanks for the offer - I already have several IPs.

Stephen?
Gary? I'm still trying to get my hands on a dead fsd; I've been following your progress, which is great as I expected. Repairing failed fsd's is a good way to go until we get a proven upgrade, which is seems around the corner... :D

[gmctd]

Remove the FSD from IP or Cooler, turn it over - the two plastic covers can be popped off the driver transistors, exposing the fastener nuts, two per transistor.

I left the covers off my repair - the covers are usually for insulation, where the transistor case is at some potential above or below 'ground' potential, and may be exposed to accidental shorting.
Here - dunno - maybe it shields the cases from IP thermal radiation, maybe not.

[Randee of the Redwoods]

Ok, gmctd. I have 2 fsd's now on the way. the first was an unknown "bad", the second the seller clearly states threw a code 1217. That was the type of failure pump I was looking for. Since we now know the "usual" codes signifying early fsd failure, I can take this new found knowledge about the loose screws to the certified code thrower and see of the theory fits.
PS-I still need your address to ship the fsd's.

[gmctd]

Is anyone keeping track of the Stanadyne p\n on the FSD's?

30214 is '94 - '98

34264 is '98 - '99

34583 is '99 - '??

34583 is the supreme acme pinnacleness of FSD design - be of prime import to determine which series set the max failures.
And the max recovery.

Will do, Randee. Been puttin' out fires at work, so the important stuff (gummint work) gets shuffled.
Either or both of those is candidate for re-torquing and re-use - you want to give it a shot at your end, first?

[GARY PAGE]

I LOOKED UP THE INSTALL PROCEDURE ON THE FSD BOLTS TO THE FSD COOLER BOLT SPEC AND IT SAYS 23 INCH POUNDS, IT'S PRETTY TIGHT. I PUT MY NEW ONE DOWN TO THAT SPEC USING MY INCH PROUND TORQUE WRENCH ALONG WITH BLUE THREAD LOCKER. I TOOK IT EASY COMING UP ON THE TORQUE SPEC AND MADE REAL SURE EVERY THING WAS CLEAN AND FLAT PRIOR TO STARTING. BILL HEATH EXPRESSED TO ME THE IMPORTANCE OF MAKING SURE EVERYTHING WAS FLAT AND TRUE PRIOR TO MOUNTING. I MAY BE MISTAKEN; BUT I THINK BILL MAY HAVE TOLD ME HIS WERE JB WELDED DOWN AS WELL, NOT SURE I HAVE THAT ONE RIGHT.

[GARY PAGE]

THE FSD THAT STARTED THE STALLING TRICK ON ME WAS THE LATEST 34583.

[BETA]

Gary!

Why would you use thread locker on your gismo device?

[gmctd]

Tsk! Tsk! Be nice, BETA - we call it a 'Cooler' here. ;)

[BETA]

Sorry, I just thought it was the southern expression for a cooler :cool:

[ 11-13-2003, 08:54 AM: Message edited by: BETA ]

[gmctd]

Touche'! :cool:

[BETA]

There's another thing we have to consider regarding FSD reliability.

I have observed this phenomena several times.

With the engine under full load the smoke suddenly leaves the harness, and the engine dies instantly. The wires change color at the same time.

If we could figure out a way to put the smoke back into the wires, I'm sure the engine will work again.

Any suggestions?

[gmctd]

Considering the number of posts on Black Smoke\No Power, perhaps an exhaust shunt, controllable from the driver's seat?
It would have to be reliable, tho.

[rjschoolcraft]

That's the problem with every electronic component I've ever seen...once you let the smoke out, it doesn't work anymore. :D Also, when they go bad, you often find bits ;) all over the floor. smile.gif

[gmctd]

Hole bytes, sometimes......

[BETA]

It's a shame you can't split a beer on the net :cool:

[gmctd]

:rolleyes:
Wish I could fax you a Coors...

And now, for something completely different -

Did the 'cremating' harness failures result from similar failures in the FSD?
Were the drivers still functional before the harness smoked?
I had stated <30amp solenoid current draw, but that was @static condition. Wouldn't take long for 30amps to ruin the harness, also - seemed as tho the IP harness may have been a 'fusible' link to protect the main engine harness.

[ 11-15-2003, 05:07 AM: Message edited by: gmctd ]

[Kennedy]

Originally posted by BETA:
Gary!

Why would you use thread locker on your gismo device? This is the same question I often ask. People cannot seem to grasp that the screws are NOT backing out. The plastic is compressing, and/or the screws are stretching. A threadlock ensures that you will never know whether it is tight or not when revisited...

[GARY PAGE]

One DP member mentioned he used thread locker so figured I would try it as well, original FSD failed without it. When I purchased this FSD cooler I did not intend to create yet another work item, guess that was a mistake. Check every 3000 miles or 3 months which ever comse first. I now know the bolts play a roll; but there is more to this story than the retaining bolts. Maybe a pair of large clothes pins would help!

[Turbine Doc]

Hey guys I've been off the page for a few days,
here is one more to add to the mix, My FSD was replaced at 37K with a cooler mounted one, ran to 45K no problems, started acting up sporadic cut out/restart when cool, I packed the cavity around the transistors with dielectric grease, but did not pop off plastic caps.

Now at 76K no problems since last event at 45K, I did not know then caps come off or that nuts were under caps. Is Dielectric grease a better cooling medium than potting compound, or did retightening of FSD to cooler plate screws correct the problem? Afraid to take it off the plate and pull caps for a look see, it it ain't broke why tempt it?

FSD is on DSG's plate remote mounted behind driver side battery, where "old style" gasser washer fluid res. would go.

[gmctd]

Could be just connectivity - r&r'ing the connector is the cure sometimes.
I'd check the driver nuts, just as a precaution, even on a new FSD.

To all -
One caveat, here - do not over-torque the nuts, thinking to avoid problems at some later date.
The driver leads are bonded thru the case with ceramic insulator - don't want to shatter the hermetic lead-thru.
Usually, with a used FSD, 1/2 to 3/4 turn is sufficient.

[BETA]

Very true gmctd! I think the only reason for re-torqueing is to get good electrical contact, not to increase thermal flow.

The lesser the better.

[ucdavis]

1) Popped caps off a known good FSD this a.m. & found all 4 driver nuts just slightly bettern' finger tight using a bare 1/4" socket (no wrench). #34583. Know its good cuz BillH used it to get roadable after stall trouble.
2) I agree that overtightening presents risk to drive/PCB connection.
3) New theory FWIW: Driver heat xfer is from driver thru SS screws & by conduction to FSD-side heatsink in the driver wells, & FSD-side heatsink is conductive to get heat to another heat-wasting heatsink (IP or Cooler). This causes drivers to heat the PCB to some extent on the way to conducting heat to a wasting heatsink, possibly killing marginal PCB parts or connections or creating intermittents. Here's the theory: The driver can is recessed into the FSD, w/the free side of can recessed about 0.080 from the FSD-side heatsink mating surface. I.e. it would take a heat-conductive shim about 0.081 to include the driver cans directly in the FSD Cooler contact surface so that the drivers were wasting heat directly to the IP or Cooler. Due to variances in the cans, ceramic shim between drivers & FSD, kep nut torques, etc., this shim would need to account for some level of variance (be a bit spongy or otherwise variable in thickness), and still have the property of heat conductivity to the Cooler. E.g. a highly heat conductive potting compound could be built up on bottom of cans till it protruded beyond bottom of FSD heatsink, then be machined off flush w/FSD-side heatsink; potting would then contact Cooler directly to waste heat directly w/out so much going into the PCB. Thoughts?

[gmctd]

A TO-3 ceramic insulator pad is available, ~.035" or so, that could be used with the new thermo-jelly(?) FSD pad.
Would take two each ceramic with layer of t-jelly top-middle-bottom to make up the dimension on each driver.
Seems possible @ first thought.

[GARY PAGE]

Sounds good just one thought came to mind. The case of the TO-3 package is the collector and in what has been described as a Darlington PNP pair says the collector drives the IP solenoid and is at system potential when the transistor is turned on. Allowing the collector to short to the IP case or the FSD cooler is going short out the collector, not a good thing and cause the famous smoke Beta speaks of. I think the case of the TO-3 must be electrically insulated from ground. I still vote for removing the transistors from the FSD package and mounting them just outside the FSD case on the FSD cooler using insulators and hardware and keeping wire length as short as possible. Crude Drawing below:


fsd cooler > fsd >>>> q1 > q2
_____|--------|____/--\__/--\____
|________________________________|

[ucdavis]

Maybe I don't understand (Ok, so that's a big understatement, but you can stop laughing now. Really, you can stop.), is the transistor can not grounded thru the screws?

[gmctd]

ucdavis
The transistor case is also the Collector connection - the cases are tied directly to the Fuel Solenoid via the screws thru the pcb, pulling the solenoid up to +12v thru the emitters.

No laughing matter (really!), the cases are insulated from the FSD heatsink, which is insulated from ground by it's thermal pad.
The FSD mounting screws are insulated from the heatsink by a layer of plastic and potting compound.

The dual ceramic pads and the new thermo jell pad should accomplish what you were suggesting, tho.
I have not seen the new pads, as of yet, but BETA'S description sure sounds like a welcome solution.

[BETA]

gmctd!

Please mail me your address and I'll send you some.

[gmctd]

Will do, BETA, and thank you.

[MTTwister]

Still learning 'bout my truck,etc. Question - if heat dissapation is a problem for the transistors: would it help, using the cooler, to drill holes in the cooler where the transistors would line up, giving them some access to air flow?

How 'bout a computer pentium-chip type fan in addition to the holes?

Or don't I begin to understand the problem?

[gmctd]

MTTwister
Heat does cause the problem - Summer underhood heat can approach 300deg from the exhaust manifolds and turbo, even after the engine is stopped.

Cooling down to ambient temp, the cycle repeats each time the vehicle is driven.

Over a period of time this causes the plastic potting compound to settle, reducing the as-torqued dimension required to maintain electrical continuity between the driver cases and the printed circuit board.

Exposing the transistor cases by venting the Cooler heatsink would probably result in water-damage failure - oxidation, corrosion, case-to-ground shorts, etc, - and other types of foreign material damage.

Thermal conductivity is from the driver cases to the heatsink, then from the heatsink to the IP or an external Cooler.
Maintaining that path will ensure intrinsic thermal stability and electrical function.

A small fan blowing across the Cooler could certainly help, particularly during periods of repeated heat-soak, as in short tripping, or being stuck in stopped traffic, etc.

[richard7]

Anybody know if the PMD wiring harness has to be replaced when the dealer is replacing the PMD under warranty?

I remember having read sometime ago from JK that the wiring is now coming standard, with each new FSD, because Stanadyne is saying that the connections/wiring are often the problem... There was a complaint about the increase in price too...

On mine, they replaced the PMD but only checked the wiring, saying it's OK. :rolleyes:

[Marty Lau]

okay my FDS has been acting up doing the intermittet stall problem. Sunday it died 8 times in 13 miles, 5 times on return trip. :(
So I ordered extension and new FSD and mounting heat sink from Bill Heath. Last night I removed FSD cooler from intake manifold and then removed FSD. Both the FSD mounting screws and the transitors screws not too tight. So I tighted everything as tight as I dar go and remounted and started hauling water. 3 trips 20 roundtrip miles.
Hauling 5,000lbs on each return. I full die and one quit and start running then nada everything work good. :rolleyes:
So I going to mount new Heath set up and keep old FSD for spare. I'll sell my old FSD Cooler for half price if anyone is interested.

[G B Sisson]

Turbopower, I have the same plan with the same exact parts,but isnt the FSD on Bill Heath's plate epoxied onto the aluminum plate?Has anyone replaced an FSD on this setup? My BETA setup currently installed on manifold has the newest gell type heat transfer pad,which seems like a good idea,but of course the issue of heat soak on manifold.I plan to mount the Heath setup on my skid plate,but maybe it's a good idea to keep the BETA Cooler along with the FSD as a spare since the Heath type uses epoxy. Heath's remote with BETA's heat transfer pad seems ideal...or should I mount BETA Cooler on my skid plate with Bill's harness??? Life before stalling was so easy,just jump in the Burb and Cruise--------- Thanks so much to all for all the help, this TDP Newbie Really appreciates your knowledge. G B

[Marty Lau]

Bill Heaths FSD set up the modual is JB welded to the plate. Bill claims very good results and says he has been doing this for folks since 1994 with good results. So I am hopefull. Maybe I should keep the cooler and modual for a spare. If I keep it for a spare tho I will remove it from the engine and remount it if need to be put to work.

In talking with Bill Heath he says the Beta cooler will work but had a number of suggestions if one is to use the Beta cooler.

1. locate it out of the engine comartment to keep it cool, skid plate, frame rail, under A/C outlet in cab what ever just get away from that gaint heat pump Diesel.
2. Grind the paint off the cooler where it mounts for better heat transfer.
3. Sand the mounting surface of the modual with 80 grit sand paper to help with heat transfer.
4. JB Weld the FSD to the cooler and let it cure 48 hours before install

If I had not fried the FSD I currently have I would have just got the extension and mount the cooler some where down under. As it was I need the Extension $90 and FSD modual $275 from Kennedy(on back order) FSD from Gomers $305. Bill gave me a discount since I was ordering a several other items so I got the whole works for less than the extension from Kennedy and FSD from Gomers. Even not discounted $395 is better than most places. JK wants $510 plus shipping for his kit. I think I paid Gomers like $445 for FSD and cooler a year and half ago and they don't have the extension available.

Bill also includes a Fuel Calibration resisstor #7 which he claims is "better" choice for most of our trucks. (not sure what to really think about the fuel resistor issue)

[ 11-21-2003, 11:35 AM: Message edited by: 16ga SxS ]

[BETA]

16gaSxS!

I have a hard time believing that Bill Heath would recommend anything like that.

It is very important, for heat transfer reasons that the mounting surface is absolutely flat. Who in this world, would be able to sand down the anodized layer (it is not paint), which is very hard, and maintain the flatness? What kind of improvements would be achieved if it had been possible? We are talking about a 0.01 mm or 0.0004 inc thick layer.

We tried epoxy in the early days, but we felt that replacing an epoxied unit must be hell. In addition, it doesn't transfer heat as good as our phase change pad.

No wonder that people are confused.

[Marty Lau]

Beta;
I understand, when I removed the FSD and tightened everything I noticed that it was NOT paint. I don't think I would do the sand or grind thing, but I would relocate the Cooler the intake mount is not good. The part of the intake that is vey close to the FSD modual and tranfers heat dirrect to that damn little black box. (yeah I know there is a a couple of cm of air between them)
I'm also begining to think maybe the pump mount is better than the FSD cooler on the intake.
The Beta cooler is about 1 kg (2lbs) and is mounted to the hot intake manifold. The fuel pump is about 10 kg (22 lbs) and has fuel running through it. The PMD on my fuel pump lasted about 100,000 miles before dying, the last FSD on the cooler lasted about 20,000 miles. Several other folks around here have had drivers die on the Cooler mounted on the manifold within 20,000 to 30,000 miles. It looks to me that remote locate the drive and cooler to a spot out of engine compartment is needed to get any reasonble life from these little back boxes.

[BETA]

The intake doesn't transfer any heat to the FSD what so ever.

Referring to the weight of cooler and pump is irrelevant in this matter - we are not dealing with accumulation. I suggest you read Jim Bigley's FSD cooler article and this topic from the beginning.

[GARY PAGE]

And pigs fly Beta! I agree 16ga. In the summer time after a hard pull you could not put your hand on the thing while mounted on the manifold how hot is that. When mine started acting up I thought it was fuel related cause it seemed to happen when I stopped to fuel up. Now I realize it was heat soak as a result of stopping for 15 minutes to fuel and take care of business. Mine is relocated behind the headlight and it a lot cooler. Enough of the square root of the hypotenuse stuff. It

[G B Sisson]

Gosh! Did I start something?Seems the most important thing is to get the FSD off the engine(or is it to keep the screws tight?)...I think both.I'd like to do my relocation job this weekend,so I think it's Bill Heath Kit on the skid plate. Since it wont get hot,it most likely wont fail,so it does'nt matter that it's glued on.End of story?... somehow I dont think so! tgif,Gary

[Marty Lau]

Originally posted by BETA:
The intake doesn't transfer any heat to the FSD what so ever.

Referring to the weight of cooler and pump is irrelevant in this matter - we are not dealing with accumulation. I suggest you read Jim Bigley's FSD cooler article and this topic from the beginning. Been there, done it, read the article when it first came out and later when I installed the BETA cooler. I have been following the this thread all along, but I didn't get the T-shirt.

I may not be an engineer, however I do know that heat rises and that the engine dirrectly below the FSD produces heat there for the intake most certainly transfers heat both by convection and radiation. I really don't know if in fact the weight (mass) of the pump is or isn't relevant. What I do know is that myself and others have had failures of FSD with them installed on the intake as per BETAs instructions and many times faiures have occured sooner than with the pump mounted driver. I do NOT believe that a BETA cooler mounted on the intake is "the answer", as proven by on going failures even with the cooler. I also believe a BETA remote mounted cooler is a better install than what I did. I wish I would have scrounged up the extra $90 bucks to get the wiring harrness extension when I bought the cooler to begin with.

I do appreciate all the work that has gone into solving our Fuel Driver problems by EVERYONE who has made an effort to improve things. If this system was designed properly to begin with we would not be discussing this.

[tom.mcinerney]

16Ga raises a real issue. Frequently the OEM FIpump/PMD lasts more than 100K Miles. Sometimes a renewal [of either/both] is a relatively permanent fix; sometimes after the first failure a renewal only lasts 20K miles. The BETA FSD Cooler is not the CAUSE of the 20K failures, a number of members have found the Cooler solved their problems. Unfortunately, electrical levels/ connections/noise, and fuel flow, and underhood heat all can contribute to repeat failures. And the OEM+current-replacement FSDs are not good enough, a result of both poor design and poor QC in production.
The good news is that Beta may soon offer for sale a much-improved replacement Driver Module, which he's designed+developed. This should preclude further 20K failures.

[BETA]

To my friends,

PCB and transistor temperatures are what counts - nothing else.

Disregard under hood and FSD cooler temperatures. Net heat transfer goes from warm to colder. When the engine is turned off, PCB and transistor temperatures (always higher than ambient temperature -

[jjgmc96]

I have my failed pmd and checked the transister nuts and they we're loose, I have not retried it yet. Are the new heat transfer pads availible yet? Have not seen them listed on advertisers pages.

[BETA]

Please call DSG

[tom.mcinerney]

JJ: I called DSG
{Visit our web site at www.dieselservices.com (http://www.dieselservices.com) or
E-mail us: sales@dieselservices.com

Call: 1-800-667-6879 Fax: 1-306-242-5457} Wednesday, they referred me to a distributor in my area, who mailed me an 'updated FSD heat transfer pad' which arrived today(Sat), not expensive.

[DAVE FERENCZ]

Who is DSG. Who is Bill Heath. Who has the best cooler. Ebay has one 400.us Mount to manifold. Includes cooler, harness, new fsd, #9 resistor. Fsd is pre mounted with epoxy compound. I mentally screwd. Can somone say there's works?
How? When? Where? and $

[autocrosser]

Why not just mount the FSD to the heatsink with standard heat transfer compound as used under most transistors. It's very efficient and gives complete coverage with no air gaps. The one I mounted on my sons truck and mine (unfortunately my original just failed after 93k miles) is mounted this way and there seems to be no temperature differential between the large home made heat sinks (8"x 5") I made from a inverter power supplies and the FSD.

I guess I'll be heading to the dealer for a replacement pump shortly as it's showing a 1216 code and one other and still under warranty. Hopefully they will replace the whole pump. One dealer I talked to said only the defective part so I'll try another.

[BETA]

tom mac 95

Thank You!

[gmctd]

Gary -

Here is a suggested procedure for working with the FSD.

If you have access to a Pace or equivalent desoldering system:
The tips are 0.125" od; one tip is about 0.120 id.

Using this tip in the heated tool, lightly force it down into the potting compound, such that it will descend over each transistor lead.

Do this incrementally, without vacuum - the heat will powder the compound, and you can blow it out with shop air, or brush it away.
Continue this until you reach the pcb circuit pads - Base is 0.062 diameter, Emitter is 0.125 (approximate).

Caution - the PCB is only 1\4" below FSD cover.

Change tip to the 0.030 id, desolder the connections.
Use resin soldering paste, and reflow resin core solder, if necessary.
(That's 'rosin', for all us shade-tree techs) ;)
The potting compound also covers the pcb back side, wnd will prevent easy solder removal.
When you can see full clearance between the leads and the plated-thru pad holes, the transistor can be removed.

It may require some force, due to the potting compound settled into the Base\Emitter lead bores in the heatsink.
I used long-nose Vise-grips lightly clamped on the driver cases, with a flat-end allen wrench to push the leads thru.

The potting material can then be carefully drilled out to provide wiring access.

The drivers are oriented 180deg opposite, for easier paralleled Base-to-Base and Collector-to-Collector connection.

I do not think remote-mounting the drivers away from the Module, and\or higher wattage devices, is a solution.
The above procedure, or equivalent, should enable further testing in several directions, if desired.

BETA's testing has been much further in-depth than mine, and reading between the lines, the failures would appear to be more of an oem procedural\quality control problem.

Snugging up the driver nuts on a used warranty- replacement FSD was my fix, after examining my failed Module.
Beta stated he achieved the same results on several FSD modules.

Now - just think of all the repairable FSD modules out on garbage dumps around various Stanadyne repair centers and GM service centers.

Sorta makes ya want to get into a "Sanford and Son" routine, don't it? ;)

[ 12-04-2003, 05:32 PM: Message edited by: gmctd ]

[GARY PAGE]

So you are saying we don't need space age components; but a part that has a quality fit right?

[Marty Lau]

BETA;

I am sorry you feel that the "quality" of this discussion has bottomed out. Many of us do not have the technical knowelge or training as you and are simply trying to get a handle on this problem. I'm sure it is frustrating dealing with non-technical folks like myself. I find it just as frustrating when I see something that just doesn't make sense to be told that what I have observed doesn't matter. Just making a simple statement like temperatures doesn't matter doesn't bring much faith when for the last 3 years the talk has been to keep the FDS cool for reliablity.
I maybe dense but when you have and engine that is running at a temperature of 190 degrees and the FDS is at 136 degrees per June 2000 article then wouldn't the engine (hotter) tend to increase the Temperature of the FDS (cooler)?
You stated that "net heat transfer goes from warm to cooler". So why isn't the warm 190 degree+ engine transfering heat to the cooler FSD & cooler? Again, I just don't understand why.

Thank You for altering us to the problem of loose nuts and screws on our FSDs. I tightened mine and seems to have helped. I hope you are successfull at make a better FSD and if you do will buy one, just as I bought a FSD cooler.

[CareyWeber]

What nuts is everyone saying is loose?

Choices:
1. The four (screws) that mount the PMD/FSD to the pump or cooler.

2. I thought I heard of nuts under the transistors mounted on the pump side of the PMD/FSD have to remove the covers to get to.

Sorry, but I need to get this cleared up for myself.

Carey

[Marty Lau]

Carey;

Both sets on screws that mount the modual to the pump or cooler and the nuts under the covers you referred too.

[Randee of the Redwoods]

gmctd-I have received the first ebay pump. I think this one is the one that was stated as throwing a code 1217. It has a white sticker under the metal manufacturer tag that has a 1998 date on it. The pump is DS4831-5288. PMD#34583. The 4 PMD screws seemed to uniform in their tightness as it took the same effort to loosen them all. A 90* turn and they were removable by hand, if that much. All connections look good, it sports a #4 resistor, and the wiring harness also looks good. I will attempt to gain access to the transistor nuts but you'll have to tell me where they are. As it stands now, the PMD is off, flipped over, with nothing there. Two large black diamond shapes I guess are the transistors. Is this what removes? Do they just pry off?
The surface under the PMD is unscathed. There is some gray matter on the pump and looks good, untouched.

[Randee of the Redwoods]

Figured that out. The covers are just little plastic things. One wobbled when touched, then fell off. Three of the transister nuts were 90* to loose, one was 180*. I retightend them to seated+180* turn. I remounted the PMD on the pump, and tightened the screws to seated+90* turn. I tested them and it felt darn close to how I found them to begin with. They were actually less tight than that. I then reset the screws to seated+180* turn. Don't know what else to tell you. Having problems with my oil pressure gauge right now(reading less than 20 pounds at idle) and some major exhaust work is coming up so I'm not in the chancy mood of swapping this PMD on to see if it works. Give me about 2 weeks.

[gmctd]

The 34583 plastic case seems to cinch the screws in place. All Torx screws in my two modules have been difficult to remove - may be part of oem improvement process.

That oil pressure is normal - idling hot is minimal 7 to 9 psi, iirc.

Attach any replacement\test FSD to a remote heatsink for your tests - makes it a bit more do-able, imho.

[moondoggie]

Good Day!

Thanks for "FSD, PMD, PMD, FSD -or- It's 10 pm - where is your FSD?" It looks like lots of FSD/PMD's have a pretty simple mechanical fix, which in hindsight isn't too surprising.

At one point it looked like some were considering re-engineering this part (heck, I wanted to do it too). Be aware there's a HUGE difference in liability between what's been done so far (advice to fix a high percentage of units, by their owners - liability ≈ 0) & designing a replacement part, potentially for sale (liability - sky's the limit).

I can't wait for the next revelation I'll find here.

Blessings!

Brian Johnson, #5044

[Randee of the Redwoods]

Idling 7 to 9 psi? You're kidding, right? And to think I started sweating like mad when the gauge first dropped below 40.
What's iirc? I'm not up on all this acronym mumbo jumbo lol stuff.

Hey. A thought just occured to me. I've taken apart(read: destroyed) many an electronic device in my time. MANY electronic devices. And I just now realized something. Those shiny nuts looked familiar. I've seen them hundreds of times in car stereos, old VCR's, even an old clock radio(I like to look inside to see what makes it work). Those look just like the nuts on the heat sinks of TEMPfets and MOSfets. Especially on the old vcr I took apart, there were dabs of translucent green stuff on the screw head or nut. I guess it was a kind of thread lock. Too many cycles of expansion/contraction would work them loose so the assembly line put that stuff on. Tough stuff, too, as I remember some of those nuts being a bear to remove. Whaddya think? Am I on to something? Am I crazy? Could that simple green dab have been the final defense against so many fsd problems? Am I just thinking about this way too much?????

[gmctd]

If you'll remember, those devices were fastened to a metal or aluminum chassis or heatsink of some form. The green, red, ect lacquer was indeed a lock-tite, where the mounting component was metallic, solid, un-compressible.

The FSD transistors are mounted and connected to the pcb thru a layer of fiberglass\epoxy and a layer of epoxy potting compound, which has a compression, or "crush", factor per inch-pound of applied torque to a fastener.

Jeffreydmet and ucdavis had covered this back on page two, including fastener torque and lock-tite.

If the oem factory did not lock-tite the nuts, were they assuming the applied torque would suffice under projected temperature ranges, or did they know the nuts would eventually need re-torquing?

Only the Shadow knows.....

[ 12-04-2003, 05:34 PM: Message edited by: gmctd ]

[GMCfourX4]

BETA;
Getting back to what you had said about the intake temp not mattering.... Is this b/c the most critical temp is much higher than the ~200* that the engine might reach? What kind of temperatures are we looking at on the individual components, and how high of a temp. can they maintain internally without failure? From what you said, and it seems others may be confused on this point, I get the impression that the transistors and PCB are getting to significantly higher temps than the engine does, so even in heat-soak, the engine would still be cooler than the components of the FSD.
Has there been any progress made on trying to get some kind of heat transfer material in contact with the transistors directly, or is this even worth trying?

-Chris

[Randee of the Redwoods]

Me thinks they were being cheap. My guess(and really it's anyone's guess) is for some reason they thought that the simple star washers would lock the nuts in place sufficiently against the vibration encountered. I don't think this is a heat issue at all, or at least not as much as some are led to believe. There is plenty of stud left, compressable plastic or not, to warrent the use of loctite, especially considering the high vibratory(heh heh heh...I said "vibratory") nature of the environment in which this device resides. Truthfully, I don't think a simple start washer would be a good enough defense on loosening in such a bad place. A dab lf Loktite green would do the trick to a new piece or newly tightened nuts. The green is intended for assembled screws and nuts AFTER tightening. I've used it before and it worked well for me. I don't see why they could not have done that. I see it all the time in ESC's for my radio control cars and inside old car stereo amps and vcr's. If, in a device like that, it was felt that lock washers AND locktite were necessary, why are we missing the locktite?

[kowsoc]

Well my Dad's 96 had stalling symtoms. I told him that the FSD transistor nuts may be loose and low and behold he said he could have loosened them with his fingers. He tightened them up and has not had a problem since. Time will tell....he also carries a used spare. I asked if he check those nuts and he said they were also loose! The DP definitely worth the price of admission. ;)

[ucdavis]

gmtd-
I have a 12V DC power supply that has a heat sink and two similar transistors w/diamond shaped caps on the back. I took the thing apart & found that the two pins (that connect the transistor electrically to the electronics) sit in tapered sockets, w/a friction connection. Are the FSD transistor connections also friction sockets or are they soldered to the PCB? If the latter, I'd say that overtorque of the kep nuts is troublesome, but if the only danger is crushing PCB @ the head of the SS screw (cuz the pins will slide a bit in a socket), then it would be much harder to wreck solder joints or components on the PCB by mild overtorque.

[gmctd]

Hi ucdavis

Those spring-connectors are excellent where minimal temperature change and little vibration are encountered, but can cause many problems if the assembly requires potting.

The Base and Emitter pins are soldered into the FSD pcb.

Because of the epoxy potting surrounding the pcb, and anchoring it to the heatsink, it's a possible 50\50 chance whether the pin\solder interface will shear, or the ceramic hermetic seal at transistor case-to-pin will fracture\shatter during over-torque.

Beta indicated to turn the nut about 45 degrees (about 1/8th turn) to re-connect thru the oxide, Jeffreydmet indicated about 3" lbs re-torque.

I'm inclined to agree.

I would like to get a reference on the 45deg vs measured 3"lbs, if anyone has a torque wrench in that range.

[ucdavis]

The 45 vs 3 lb result will depend on the snug state of the nut pre-torquing. We are likely to define snug a bit differently, so 45 degrees past snug is a variable end result, whereas 3 lbs (assuming clean threads & square mating surfaces) is more precise.
In high-rise steel framing, the standard ASTM method is called Turn-of-the-Nut. You get nuts "snug", defined as connected pieces in contact & nut as tight as an ordinary man can pull on a spud wrench, then turn them an additional 1/3 turn (for which you need an extraodinary man or a longer wrench handle). But you can see that thread oxidation (accounting for, on occasion, up to 90% of torque req'd to turn a nut according to ARP), joint fit, and the judgement of the installer are all variables, as w/the 45 degree past snug method.

[gmctd]

I believe the intent was to run the nut down by finger, then turn the nut 45deg with a nut-driver\socket wrench.
I would like to see how that equates to 3"lbs torque.

On another, one FSD you checked for BillH had a mixture of kep and non-kep nuts.
If the non-kep's were of the serrated face variety, they should functon to make connection thru the oxide. Would still require re-torqueing.

If they were normal smooth-face variety, that could explain the spate of early failures last year, or so, where supply and demand resulted in shipping assy's with standard nuts.