Rough starting 6.5TD

[sprice]

I have an interesting problem, and I hope someone can shed some light on it. Ok here it is - I have a '95 6.5L TD that I have replaced the block with a punched out 6.2, new 6.5 heads, upgraded the cooling system to the dual stats and high flow pump, I have replaced the PMD, the fuel pump, fuel filter, injectors, and had the Injector pump re-calibrated, replaced the glow plugs, and installed a new oil pressure switch. I took it to a local shop and had my timing offset adjusted and even had a cold compression test performed. My cold compression is around 350 PSI avg. on all cylinders - this is quite low, but the truck runs great when it is up to temp.
-My problem is most of the time when I start it, it fires right up sounds great for about 3 seconds, then it will either start to idle real rough and blow out a ton of smoke for about a minute before it idles normal and has clear exhaust - or it will stall and not want to fire up again.
-One concern I have is the sequence of the glow plugs. Are they suppose to keep cycling after it starts like the old 6.2s or is it done with it's warmup after it starts?
-My other concern is my injector pump. Could something be jacked up from the injector shop?
Once I start driving it though it has no problem starting or running until it has sat over night. Can someone shinesome light on my problem???
Thanks.

[DmaxMaverick]

Sounds like you have an air in fuel problem. Check the filler cap. It should not retain much, if any, vacuum in the tank. Any vacuum will exploit any leak in the system, and air will be sucked in, causing exactly what you are experiencing.

The glow plug system isn't that complicated. Once the engine is running, they are not needed at all in moderate tempuratures. The "after glow" is more for the EPA than smooth running, except in extremely cold weather or very high altitudes. I can't imagine it being too cold right now, just about anywhere you could be. Even so, without afterglow, it should smooth out in a few seconds in the worst case, in above freezing temps.

350 PSI is not low by any means. It is more important that the high/low between all cylinders is in range. If they are pretty consistent (within 15%), then no worries. The compression should be checked on a hot engine, not cold. Your compression will be higher when hot. Cold compression checks are usually inconsistent, and cause many false alarms.

If your fuel system and fuel cap checks out, you have a leak somewhere. Usually, it's the filter or a connector. If you have no fuel weeping anywhere, it's likely before the lift pump. The slightest drip of fuel after the pump will translate to a large airleak once there's a vacuum on the system, like sitting overnight.

[sprice]

If I were to put a pressure gauge in-line to the injector pump, in theory it should hold pressure - correct?

Thanks for the tips.

[DmaxMaverick]

Yes. But not forever. When you shutdown hot, the fuel (and the air in the tank) is hot, and expanded. As it cools, it will contract, and eventually draw a vacuum. If the cap is no good, it will not vent properly, and build too much pressure, and/or vacuum. The cap should vent pressure at about 2 PSI, and vacuum at about 2"Hg. If you are going through the trouble of installing a gage, use a press/vac gage to see the whole picture. You can also monitor lift pump performance at the same time.

Rather than T'ing into anything, just install the gage at the fuel filter drain tube. Leave the valve open, and the pressure/vacuum will be in an ideal location to monitor.

[Cowracer]

Also check your IP timing. An out of time pump will make for a hard starting truck.

Tim

[sprice]

I had a dealership setup the timing. I just replaced the fuel cap, and I have looked everywhere for leaks. I am still having a hard time getting it to fire right up the first time. I have read in another spot where you can put the truck in drive and turn the key to prime the filter. I have been doing this and after the second attempt to start it, it will fire. It still runs rough until you hit the gas and get the turbo to spool up, then it runs just fine. It will have no problem starting the rest of the day, until it has sat idle for about 8hrs, then it's a battle all over again. Anymore ideas? When I had the pump recalibrated, I replaced the fuel lines from the filter to the pump, and from the filter to the water drain. My shutoff for the drain was leaking when I first tried to start it, but I pinched off the hose and put a zip tie around it until I can replace it.

Should I try replacing the filter again? Maybe the rubber seal is bad.

Should I maybe run a new line from the pump to the filter housing?

Is there a pressure switch that turns the pump off after it hits pressure?

When I replaced the fuel pump, I bought an aftermarket Carter. Would a exact replacement from the dealer be any better? I wouldn't think it would.

[Robyn]

What Maverick is telling you is right on.
Now before you go off witch hunting, fix that drain valve. Having that line pinched and zip tied could very well be the source of your air leak.

Air, even in very small quantities will make these suckers run horrible until its purged out.

Make double sure your fuel system is absolutely top shelf and then see what happens.

Here is the deal, if the IP has an issue its most likely going to have it all the time and not just during startup.
If there is a serious issue the Computer will see it and start screaming. (SET A CODE)

All the fuel lines need to be in good shape. The filter is most likely ok. If it had an issue it would probably leak as it runs under pressure.

Another area of concern is the lines that run from the electric pump on the LH frame rail to the filter.

Are you sure your lift pump is working right. It needs to start working just as soon as you turn the key to the start position.

The lift pump should hold about 5 psi in the system when the engine is running.
A quick test is to open the drain valve on the front of the engine with the hose in a can, if the engine stumbles and dies you have lift pump issues.
Fuel should flow freely from the drain with the engine running.

After a quick start cold switch the engine off, you should hear the pump running under the rig for several seconds after the engine is off until the residual oil pressure in the engine bleeds off and the switch opens.
This will only happen when the engine is cold though.
This will test your OPS for proper operation

Check these things and let us know and we can move ahead from here.

Fix all possible leak areas
Check for lift pump operation while cranking
Check for fuel pressure while running
Check for after run on pump when cold

If the pump is at all suspect, replace it

best to ya

Robyn

[gmctd]

Welcome to the 'Page, Sprice.......

Load of bad fuel will do that, but also sounds like your cold-start timing advance is not functional - have the dealer check Desired\Measured timing for 12-15deg at cold-start, dropping back as ECT increases.

If Desired is correct, but Measured is retarded, may have loose wiring or open connector or the TSM is jammed.

Alternately, base timing is retarded - TDCO should be -0.5deg minimum, with
-1.5~1.94deg is desired for performance.

[Robyn]

With all this good info, now your bound to get to the bottom of it. :D

Best of luck with the beastie

Robyn

[sprice]

With all that I have done on this truck, now it is stalling. I had previously replaced the PDM and it ran fine. But now it stalls intermittently. I have replaced the PDM with a new one and it still does it. There are no fault codes that pop up. HELP!!! This thing is killing me...

[rameye]

keep goin on the reccomended course... air in the system can still cause your symptoms...

check that fuel pressure... make sure pump is working...

Did a stanadyne shop do the job??...I always get concerned when I hear ...high performance etc.

Where is your PMD??? still on the pump???

[byte]

to see if you have an air problem... use a piece of clear tubing on the return line from the IJ pump... if you see any air after running or sitting, you know it is an air leak...

[sprice]

OK, I have installed a new needle valve on the filter drain. It was running fine, then it stalled 3 times within 5 miles. I drove it home, then went right back out an hour later to take the same 5 mile journey, and I didn't have another problem. I went out, did the chores, drove around the farm a while, then drove home with out another problem, and still no fault codes. It will even fire right back up after it stalls. Could it now be the Ignition harness I have been reading about in other posts??? I have dumped way too much money into this thing to just sell it or scrap it out. Plus I love my diesels.... I am just having a hard time loving the electronic version right now!!!
Thanks for all of your replies, they have helped out so much.

[gmctd]

The PDM acronym always worries me when someone is referring to the EFI 6.5 - the driver module is the Pump Mounted Driver when attached to the Inj Pump - it becomes the Fuel Solenoid Driver when removed and remote mounted on a heatsink.

The only guy who ever called it the PDM was banned from this site about 4-5yrs ago for extreme antisocial behavior - he continues to call it the PDM to this day, along with dishing out erronious and misleading misinformation intended to engender sales of his nefarious products.

So, on that sour note - where and how is your FSD\PMD located, and where and how is the short black wire mounted - the one that is designed to be attached to the top of the injection pump in order to meet 6.5 EFI electronic specs?

Those same electronic specs resulted in a special electronic filter being designed and inserted into the EFI DS4 Inj Pump Optical Sensor harness for noise suppression.

[sprice]

Sorry if I had two letters switched DAMN me to hell!!!! J/K... I have the Little short wire grounded to my heatsync. I am thinking the first one I had on is still good since it is still having the same problems. Has anyone ever tried to take one of these bad boys apart? How could two transistors be so expensive??? I haven't designed a lot of circuit boards in my life, but the ones I have done were not $300. I am sure it is covered in epoxy too, making it near impossible to take apart.

[gmctd]

Ground the wire to the top of the IP, then re-try both FSD's - just pull the wire back thru the harness to get the length, attach it under the top rear screw above the pad where the module was originally mounted.

Then we should talk about getting the 'sink and module outta the engine bay - the intake manifold is still ~100deg hotter than the module should be to survive.

Folks that use "PDM" have usually come from that website and have relocated the ground wire to the heasink and are experiencing erratic running and intermittent dying - so, no, hell's not the picture until you start calling yours 'the 6.5 from hell!'.

Also, do a search on PMD\FSD for more diagnosis and analysis info than you ever possibly wanted to know.

[moondoggie]

Good Day!

"Sorry if I had two letters switched..." You'll have to forgive gmctd - he has very few hot buttons, but maybe we found one, eh? ;) He's the best among a lot of real good equals, so I guess we can forgive him this.

"I have read in another spot where you can put the truck in drive and turn the key to prime the filter." Yes, but only because you've got a 95 truck. I checked - 95 is the only year that this works. If you have an assistant, I'd be tempted to suggest the following: pop the hood, put the drain valve tube in a container, open the drain valve, then have your assistant put 'er in any gear except park or neutral & turn the key to the crank position. This will activate the LP without cranking the engine. Watch what comes out of the drain tube: if you get more air than the tube itself might have held, that may be indicative of a vacuum-induced air leak. I'd let 'er run until I've gotten a good long shot of fuel, then close the valve before telling the assistant to release the key - the fuel lines should be filled with fuel, at least up to where the drain valve connects. If the engine now cold-starts & runs right, you're closer to your solution; if not, the air could be coming in between where the drain valve connects & the IP, or your problem is elsewhere. Not much lost by trying - this will only take a minute or two.

"Has anyone ever tried to take one of these bad boys apart?" Yup. "I am sure it is covered in epoxy too, making it near impossible to take apart." The potting is thermoset, so heating to incineration and / or mechanically removing it are about the only ways. It really doesn't matter; do the research gmctd suggests - I think you might wind up agreeing that it's the tremendous underhood temperature swings that are the main problem, NOT the drive transistors.

& I had to throw this in - the devil made me do it...

"The PDM acronym always worries me when someone is referring to the EFI 6.5 - the driver module is the Pump Mounted Driver when attached to the Inj Pump - it becomes the Fuel Solenoid Driver when removed and remote mounted on a heatsink." IMHO it's a FSD wherever it happens to be; it's a PMD if it happens to be mounted on the IP. ;) (Forgive me father for I have sinned; I couldn't stop myself - you can never catch gmctd in ANYTHING, so I just HAD to make this comment.)

Good Luck & Blessings!

[gmctd]

Long as the point gets across, my friend - PDM = module on a heatsink bolted to the intake manifold, with the ground wire attached to the heatsink - samo samo alla time plenty trouble, GI :cool:

[sprice]

Thanks for all the help. I will move the ground wire as soon as I get a chance to play with the truck again. Where would the best location be to mount the FSD/PMD and heat sync? I have toyed with the idea of using a liquid cooling system from one of my computers. They have a small radiator, a pump, and I have designed a custom mounting block that would act as a heat sync. I think it would be cool but completely impractical. I will continue running the tests on the fuel system and try relocating the FSD/PMD and heatsync to another location. Thanks again.
Shaun