Air in fuel solutions

[a bear]

As some folks come to a close with their testing it appears that the discussions are making a transition from stopping the air to dealing with it in a convenient way. One thing that makes this forum so usefull is that it promotes good thought and ideas. With that said when I return home next week I plan on finalizing my testing for my own piece of mind and if I still have that residual amt of air I will be eating my words and assume the remainder is outgassing as some members have already mentioned. Before completely jumping on board with the guys that are way ahead of me on discussing solutions I was wondering if it was worth while to discuss the issues with the folks who designed the fuel delivery system. I guess what I'm saying is that maybe this vac system was designed to also remove this additional air that would yeild a better fuel by volume (BTU value)and also reduce cavitation. Of coarse the Bosch LP suction pump would also have to be designed to seperate the air and send it out VIA the return line. Maybe this is a possibility worth checking into. This would be in addition to the benefit of preventing engine oil contamination with diesel. Maybe Dmaxalitech can help refer us to someone who can put us in touch with A soarce that can help answer questions. If this is the case we can go back to what we intended to do. (filter dirt)
:D :D

[ 05-02-2003: Message edited by: a bear ]</p>

[DanB]

Hi,

It looks like Bear is questioning how serious the problem of air in the system really is. To this I would like to add the question of why people are not looking at the fuel injector pump?

It seems quite likely to me that the seals on the the fuel injector pump allow air into the system. Instead of worrying about how to get it out, shouldn't we be worrying about stopping it from getting in? Perhaps I am just confused, but I would like not to be :)

Thanks,
Dan.

[dmaxalliTech]

I dont feel there is any problems with a properly functioning injection pump. Of course a faulty pump could have an air leak. I really havent seen much issue with air in STOCK fuel system. Usually problem arrises with add-on filters.

[jbplock]

dmaxalliTech,

Your signature indicates you have a MegaFilter on your truck. Are you also bleeding it periodically? smile.gif

[ 05-03-2003: Message edited by: jbplock ]</p>

[a bear]

DanB,
The air I am refering to would be very small amt's of air that resides in the fuel at atmosphere conditions and then are removed from solution due to the vac conditions. (SMALL AMTS, NOT A LEAK) If the Bosch LP pump is designed to handle this small amt and return it to the tank it may be OK. Keep in mind that only a small amt of fuel goes to the HP pump,rail and injectors. The large balance goes to the tank where the air can separate. My question being could the LP pump by housing design,outlet location redirect the air that is maybe now larger bubbles and divert them to the tank. The design engineers may be able to answer this question. The hard part will be to come up with the right contacts. If not I will also be rigging up some kind of additional air trap.

[a64pilot]

a bear,
Another thought. If it's outgassing, and I believe the majority is, wouldn't it go right back into solution at high pressure? I agree that talking to a design engineer would be the ultimate answer. Hopefully one of the ones that are reading this and possibly grinning will speak up.

[DanB]

Hi,

Thank you Tommy.


DMaxAlliTech:

We will shortly have 3 verified cases in which the fuel injector pump was responsible for allowing air into the system. At least two of those trucks had STOCK fuel systems. Additionally, given it has been plumbed correctly, the insertion of an additional filtration element should not cause these types of problems UNLESS there is an existing condition which is being exagerated.

At least, that's my take :) Perhaps someone will come up with an experiment to prove me wrong?

Thanks,
Dan.

[a bear]

a64pilot,
It's definitely possible. I always did wonder if those engineers were lurking and laughing here. :D Come on fellers, enough already. tongue.gif

[a64pilot]

a bear,
If you were GM wouldn't you set up a monitoring division say to see what the opinions and concerns that JohnQ public had? What better and cheaper way than the internet? I'm not saying they are, I have no idea, but they would be stupid if they weren't.
Dan B,
I have no doubt that any pump by any manufactorer (sp)? would pull air if the seals on the suck side of that pump were to go bad. I also have no doubt that any air seperator would be of no use in that case because the source of air infiltration would be down stream of the seperator.

[DanB]

Hi A64,

Do you have any idea what type of material the seals are made of or how the temperature fluctuates in their working environment?

Thanks,
Dan.

[a bear]

a64,
Thats a good point. You can only protect up untill the separator. You may never detect a leak down stream of that where the system sees the highest vacuum. :eek: All the possibilities, potential fixes are part of the reason I feel the need to speak to someone that may have info. about our issues, LP pump design, etc. I have to go to Houston untill Wednesday morning and will be MIA untill then. Hope you diehards will have the answer when I return. :D :D :D
Later,

[Tsckey]

While I agree completely that the fuel can never be too clean, I'm wondering if we might not be too worried about air. I will gladly defer to the greater expertise of the many accomplished and knowledgeable members here, but consider this: Assume for the moment that the fuel system, whether or not it has a supplemental filter installed, is otherwise intact and not allowing air into it. That would leave entrained air as the source of what members are trapping in their systems. Maybe the solution isn't in purging the air, but in not trapping it in the first place.

I understand that air can cause cavitation and associated deterioration of the injectors, but perhaps the problem is more theoretical than real. I know I will be corrected quickly if I'm wrong, but as I recall, Brokers has compiled over 400k miles with more than one rig without major injector problems. I believe he uses multiple filters pre-OE, but otherwise has not addressed the air problem, nor would it appear that his injectors have suffered for it. Perhaps a64 is right; when under vacuum the air can come out of suspension, but when repressurized by the injector pump it's squeezed back into a relatively harmless form.

Now, again, I don't doubt for a moment that no air is better than any, but maybe the boogey man under the bed is just fairy dust.

TC

[56Nomad]

TC,

I covered this point previously in:
http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=3&t=005713

Other than JK's valued opinion, I find no
engineering studies or papers pointing to
normal dissolved air doing damage to our injectors.
John and others believe otherwise.

You would figure that with 9500+ members on
this forum, we would have at least one
mechanical engineer who could answer this
burning question.

At this time, the absence of any documention or professional
engineering opinion leads me to believe that it is NOT
a major problem with our Duramax or Cummins or CAT or PS.

However, this is only my humble opinion and I
stand ready to be corrected.

[ 05-05-2003: Message edited by: 56Nomad ]</p>

[dmaxalliTech]

jb, Yes, I do have MEGA filter post oem. I have checked it three times after reading posts regarding air. I have yet to get the slightest bit. Everytime I open it, I get steady stream of fuel. I have put 2k miles on it and NO problems what so ever.

Dan, I stand corrected, I have just recieved information on 2 injector pumps being replaced for an air problem. I know that both trucks were fixed after pump replacement!! I do know that both trucks only had drivability issues and didnt suffer any injector damage. I am gonna try and contact some people that might have an answer or at least can shed some light....

[jbplock]

dmaxallitech,

Thanks for the report on your filter! Very interesting! Glad to hear your MegaFilter is working well and not collecting air. I guess I need to keep looking for a for a leak. :confused:

[chuntag95]

Wow, 3 times and NO air! :eek: I'd be happy if I could drive around the block without getting some. Full tank, empty tank, grease in the firewall fittings. I guess I will have to continue to trouble shoot. If you can have no air, then I can to, I hope, unless it's fuel. :confused:

Are there any differences in the 03 fuel delivery system?

[ 05-04-2003: Message edited by: chuntag95 (Chris) ]</p>

[NWDmax]

Hey Chris,I find after I pump the primer till its firm after I wait a few minutes its real easy to push.
Is yours the same way?
Checked all my hose clamps I installed with the Mega filter and tightened them down with a socket.
I don't think this will change anything butits worth a try.
Thanks for posting the link to your sightglass pics.It looks like a great idea but it sure seems we're treating the symptoms and not getting the cure.
Thanks again for all the effort we've got to be getting close!
Blake

[Lone Eagle]

Dito Nomad. Later! Lone Eagle ;)

[DanB]

Hi DMaxAlliTech,

If one of those injector pumps was mine, I'm impressed with the speed you get your information. The info on my truck wasn't punched into the computer until Friday around 5:00 pm (West Coast time).

Thank you for the update and for checking!

Dan

[a64pilot]

DanB,
I have no idea what the seals are made of etc. As I am not a Diesel mechanic by trade, I thankfully have very little pratical knowledge of the Dmax eng. Sorry I can't be of much help.
Chris,
Out of curosity is your air leak better in the morning and get progressively worse as the truck gets driven for an extended period of time?

[jbplock]

Chris,
My truck is a 2003 (with 7.5kmi) and if it has a leak it was there when I bought it or it's coming from my MegaFilter installation. I plan on working through the diagnostic procedure in the Helms manual, which will include vacuum testing of the MegaFilter connections with a MityVac. I'm also going to install a new OE filter (with Super O-lube) since I still have the original and see if that makes a difference.

Blake,
Regarding bleed down of pressure on the primer, could it be fuel bleeding through the orifice in the injection pump to the return side of the pump? I believe the orifice is there to bleed excess fuel from the pump to the return (?) The procedure in the Helms refers to this orifice in the test procedure, as the reason the vacuum will slowly dissipate during a vacuum test. I also have the GM Gauge that connects to the Schrader valve near the Alternator, and if I pump up the pressure on this gauge with the primer, the pressure drops from 10 psi (full scale) to 2psi in about 9-10 minutes

[chuntag95]

a64,
I have not seen any morning or night type of differences. The longer I drive, the more air/fumes/vapor.

nomad56,
I agree that so far we are treating the symptoms. I am hoping to get my hands around what the problem is exactly. With the question being is it air, fumes or vapor? I am a mechanical engineer by schooling and have always found it is easier for me to solve a problem if I fully understand the system. I am working towards that end, but unfortunately my day job keeps getting in the way. :rolleyes: The wife has been feeling a bit neglected too and I caught a bit last night over it. Have to choose my play time wisely. :D

I ordered check valves and adapters last night for my auto bleed pump setup. I need to go by Autozone and see if I can find the clear fuel filters like Bill found. I think I can make several air traps to help understand where the air starts to show up for a better price than the one on my Mega. That one is there for life and the bleeder will be replaced with the connection to the inlet side of my bleed pump. I am also going to run the 2 switches (momentary) so I have one in the cab and one in the engine compartment. I am tired of burning my hand on that stupid heater line while pumping. :mad: My cheap traps will only be temp until I figure out what's going on. The same goes for my clear hose. I am boing to crank down all of the clamps again tonight.
Chris

[chuntag95]

Bill,
Refresh my memory please. Where do you put the clear line according to the Helms test?

Dmaxallitech,
Figures the tech in the group would get a truck that doesn't leak. Just like those noises that disappear when you drive up, huh? :D tongue.gif

Chris

[jbplock]

Chris,

I don't have the manual handy but I seem to remember it says to put the clear line between the FICM and the OE Filter with a loop to observe any air in the line. I can't remember if it calls for other locations (i.e. after the filter) smile.gif

A64pilot,
By the way, is "A64pilot" referring to the AH64D as in Apache Longbow? I worked on a system for the Apache that my company currently manufactures.

[ 05-05-2003: Message edited by: jbplock ]</p>

[chuntag95]

Well Bill, I got some good news and some bad news. The good news is I have a hose running just as it says, the bad news is it always has bubbles in. What I don't know if if the bubbles are stuck there and the same for all time or if they are new ones. This is why more air traps are to follow. Hope I don't add so many that the truck floats away. :eek: tongue.gif ;) :D

[jbplock]

Chris,
If I recall correctly, Tommy found air in the same place. Next, he connected a hose to the fuel line near the valve cover and put the other end in a container of fresh fuel and started the engine - no more bubbles. He then replaced the QD line from the tank to the steel line with 7/16 hose and clamps, which fixed his no-starts (Tommy, my apologies if I miss-quoted you from my aging memory). smile.gif

[a64pilot]

jbplock,
Yes, I am an A and D model test pilot. Which system? BTW
Chris,
The reason that I was asking if the bubbles got any worse as you drove it is if it's out gassing or fuel vapor then it should get worse as the fuel temp increases. If it's not then I would imagine it would remain relatively constant.

[ 05-05-2003: Message edited by: a64pilot ]</p>

[hoot]

Local speed shops carry Russel see-thru filters...

Haven't found anythin larger than 3/8 though. They also say for gas only. You can remove the element and maybe even open the holes up accomidate a larger size?

http://www.russellperformance.com/automotive/fuel_management_systems/fuel_filters.htm

.
.
.
.

[ 05-05-2003: Message edited by: hoot ]</p>

[jbplock]

A64, We make the RFI (under the FCR).

[chuntag95]

Hoot,

I don't actually want a filter at all. I just want a clear, cheap air trap vessel that I can put a purge valve on top of. I can then put one in several locations and reduce my "Where's it coming from?" questions.

The goal is to know if I have a leak or am generating gas in what parts of the system. I have 3 basic sections in mind. First is the tank and line to the firewall, second is the crazy winding over and through the engine to the EDU and third the filter systems. They are only temporary, so I really don't want to invest a bunch in them, you know? :cool:

[dmaxalliTech]

Hey Chris, you wanna hear a funny story?? I once had a customer with a bonneville. Swears he had this complaint, I dont even remember what is was. Anyways, he brought it in numerous times and we never found anything, I went for rides with him and he could not reproduce it... Long story short. I put one of business cards on the air box lid(had picture on it) and sent him on his way. He called back a week later and said whatever we did, its fixed!! I never touched the car other then that.

[hoot]

chuntag95 (Chris),

Those filters are cheap (less than $10).
The filter element is removable.

You now have a glass vessel.

Because it's double ended, you can mount it vertical and put a bleeder on top.

[ 05-05-2003: Message edited by: hoot ]</p>

[Kennedy]

Air is not dissolved if it is accumulating in our filters. While it is true that it may well go back into solution once run through the LP side of the pump, it is still there, acting as a cushion...

May not necessarily be bad, but CANNOT be good...

[stutzismydog]

Gentlemen:
I have been following this fuel filter/air bubble topic through several hundred posts and appreciate the intellectual quest to solve a perceived problem. I am a civil engineer by training and a fair shade tree mechanic that would also like answers from the designers of our $40,000 + system,

[a64pilot]

jbplock,
Well aware of the RFI, lots better than the APR-39 "all locks stroking"

[hoot]

stutzismydog,

Great input.

I for one have a post OEM setup without an air problem. I think putting a 2 micron filter after the OEM is logical. You are only filtering 2 micron particles (mostly) so the filter will have some life.

Putting the filter in the back wheel well area poses dirt issues.

Since the OEM filter is hassle to get to, adding one under the airbox as in JK's design isn't all that bad after all.

I installed the rivnuts so pulling the wheel well cover once every 10,000-15,000 miles is no biggy.

I do not like the idea of filtering 2 microns pre- OEM. It basically makes the OEM filter obsulete.

I guess the best solution is for Racor to come up with a larger and better replacement.

And now....
For the controversial part....

Anybody having air problems with the Mega filter, replace it with a Racor 690 and see if that fixed it. :eek:

[ 05-05-2003: Message edited by: hoot ]</p>

[stutzismydog]

Hoot~
I here what you are saying about making the OEM filterer obsolete if a PER-OEM filter is installed. Just think of it as EXTRA PROTECTION.

The point I was trying to make.....is to give GM engineers some credit and not mess with their design by putting a second system POST-OEM in the fuel flow, it looks like it is causing problems.

[a64pilot]

stutz,
Anything you do is messing with their design. I believe the only filter that is exhibiting an air issue is JK's, and it's not making air or causing anything to leak or anything else. I believe it's unique design is merely trapping already existing gasses.
If you go Pre-OEM you should be prepared to spend a lot of extra money though. You will need to buy a filter head that is heated and has some form of water in fuel warning system if you want or need either of those.

[chuntag95]

Just to set the record straight for my personal situation, I have had no problems from my MEGA filter. I started looking into the air issue before it was ever installed. It does trap some of the air, where as before it was just pushed through the system. Good or bad, I can't say 100%, but I am leaning towards the safety side and removing if possible. I am currently running my system without any purging to see if I have any problems develope. Considering what I saw with my clear hoses, I don't believe I will. Even if the top 2 inches fill with air/vapor, when it starts pulling up the nipple, it should go through just like it did before. To bad they don't have a clear mega filter :eek: that would be interesting to see. I wonder what they would charge to make one of those?

My personal investment is more for truely understanding the source of the gas. Is it from the system being under vacuum? Is it small leaks? Is it related to temperature, fuel quality, etc.? I don't know if I can answer all of these, but I do think I can get much closer than I am right now. It will cost some time and money, but there are worse things I could do with both. ;)

[NWDmax]

Chris, how many miles have you driven with your Mega filter on?
I had no problems starting,idle quality or excessive air for the first 500 miles.
Thats the real confusing and frustrating for me.
The only thing I can figure is the added vacuum from the additional filter( even though small )made a small leak get worse.
When I bleed I pump up 10 to 20 times and I'm getting no air just fuel.Does that sound right?
If I crack the bleeder on the Mega before pumping I hear air but not sure if its vacuum or positive pressure.I'm thinking its vacuum because if I pump after that I get a shot of air then fuel.
Hopefully this makes sense.
Should be getting the clear hose today and start testing.
Thanks for the feedback its been a real help!

[Kennedy]

Blake,

Keep in mind that the only place that additional restriction is placed is AFTER (between filter and pump) the added filter.

I believe that the majority of any restriction comes from the work required to LIFT the fuel from the tank...

[chuntag95]

"Chris, how many miles have you driven with your Mega filter on?" Right around 550.

"I had no problems starting,idle quality or excessive air for the first 500 miles." I have been bleeding because I knew there was air in there from my pre install testing. No issues with any of the items you mentioned as of yet. I have stopped bleeding to see if they develop.

"When I bleed I pump up 10 to 20 times and I'm getting no air just fuel.Does that sound right?"
I pump till it is hard and then open the bleeder. Depending on the time/distance from the last bleed, it can be quite a few.

"If I crack the bleeder on the Mega before pumping I hear air but not sure if its vacuum or positive pressure.I'm thinking its vacuum because if I pump after that I get a shot of air then fuel." You are pulling in air. The system stays under vacuum for quite a while. I left JK's gauge on it for a couple of hours an it still had a little vacuum on it.

"Should be getting the clear hose today and start testing." Did you order yours? If so, where from? I am considering ordering 20-30 feet and running a temp line from the tank to the firewall and adding an air trap at the end.

"Thanks for the feedback its been a real help!" I'm glad someone finds it of value. I owe a lot to JK, Tommy, a64, etc. etc. etc. This is really a group effort. I wish I had this much participation on some of my college teams. tongue.gif

PS - Time to start a new thread since we rolled to page 2. :D

[ 05-05-2003: Message edited by: chuntag95 (Chris) ]</p>

[jbplock]

I have also stopped bleeding to see how far I can go. I currently have about 1500 miles on the Mega and have been bleeding every 200-300 miles. Not a single problem with starting. Given Tommy’s, JK’s, Chris’s and my test results, I’m letting myself become convinced that the passing of air/vapor is a feature of our system (RACOR also mentioned this in an earlier thread). While it’s debatable whether this air is problem or not, I think removing it can only help – not hurt. So for me, it's on to an auto-bleeder and maybe a few more tests to verify I have no external leaks. I bought a pump and clear filter along with a TBD check valve that I’m going to plumb to the Mega bleeder. For now, I’ve decided to just leave an easily accessible length of 5/16 hose connected to the output of the bleeder pump (maybe near the fender well). When it’s time to bleed every 500 miles – or longer- I’ll just drain into a small closed container that I keep in the bed of the truck. If the bleeding interval is this long, I don’t think I’ll mess with plumbing the auto bleeder to the return line. This approach with the JK Megafilter could be the poor man’s version of the Preperator. (My mileage is also up about 1 to -1.5 MPG :D )

[NWDmax]

Chris, the only place I found the clear hose was at our local Ace hardware store.
They had a very complete selection and the 1/2" id ran .79 a foot and the 3/8" id .22 a foot.
The info sheet says its chemical and gases compatible.
The auto parts and industrial parts houses had nothing in stock.I must of made 10 phone calls to track this down.Hard to believe its that difficult to get! smile.gif

[chuntag95]

I found 1/2 and 3/8 but all in 1/16" wall. I want 3/32 or 1/8. The only 1/8" wall has the braided nylon in it. :( I am about to order some that I found at a web site for USPLASTIC.COM. Talk about a complete selection :D The best stuff I found from a specification standpoint said not for fuel in the very last line. :rolleyes: Next I am going to bolt a 55 gal drum in the bed and put a hose from it to the engine and plug the return back to it. (Not really, but it does get frustrating at times.) That should stop the air.

[NWDmax]

Started the truck this morning and it did not stall.Idled rough for a bit but didn't die :confused:
I didn't bleed since the weekend,go figure!
The 1/2" was heavy wall 1/8" I think and very firm.
Sounds like you found a good source!
Good luck Chris!
I'll let you know how it goes once I get the time to do it.
Blake smile.gif

[hoot]

Home depot carries many dia's of bulk clear plastic hose.

[chuntag95]

I got the rest of the parts for my auto bleeder today. I found a couple of switches and my check valves came in too. I bought a BUNCH of different fittings of all shapes and sizes so when I mess one up, I'll have another one. :rolleyes: I seem to do that a bunch. :(
It seems that the pump has a check valve in it. I am putting a second one on anyway just to be safe. I have considered making a really big (32 oz) air trap and putting it pre Mega. It would be interesting to see how much is coming into it and be able to see the total volume. I found a plastic container with marks on it too. The only question is where and how to install it. First thing would be to JB weld a fitting into it so I have someway to attach it. Probably should put a valve on it to shut it off if needed. Anything else?

On a separate note, I have 160 miles since my last bleed. No problems, but no fuel in my sight glass for days. That's part of the reason for my larger trap plan. So far, there have been no issues of any type. I can tell my milage is up. I will have to wait to give an amount until my next fill up. I am at the point on the gauge where I would be if these were all highway instead of in town miles. :cool:

[ 05-07-2003: Message edited by: chuntag95 (Chris) ]</p>

[jbplock]

Chris,

I tested the check valve on the E8012S pump with a MityVac and it doesn't hold a vacuum so we will need the added check valve. Maybe the one attached to pump is used to self prime the pump (?).

[chuntag95]

Bill,
Thanks for checking that out. I was just going to be my conservative self and put it on anyway. :D Now there is a real reason.
Chris

[Dave Lewis]

Did anyone ever put a lift pump in to switch the system from vacuum to positive pressure? I know there was talk about it but I have not seen any posts of somebody installing one. If there is somebody running one, how has it been working (good, bad)? My thought has been to install a lift pump and use a low cracking pressure check valve in place of the bleeder on the Mega filter to dump the excess fuel and air back to the tank. I don't think 1-2psi would have any negative effect on the existing lift pump.

[NWDmax]

Keep looking on these fuel posts Dave there is a couple guys that are running a lift pump with no apparent ill effects so far.

[jbplock]

Dave,

I think a lift pump would work. The ones I found run about 6 psi. They should also be wired to an oil pressure switch to prevent the pump from running in an accident. One possibility is the AC Delco pump used for the 6.5. It is a flow through design that allows flow even when the pump stops or fails. I found a few marine rated flow through pumps in a Borg Warner catalog that also looked like they might work. However if a lift pump is used, the air will still be circulated and/or kept entrained in the fuel (?), which will prevent air/vapor buildup in the filter. But

[a64pilot]

Dave,
I'm on the sidelines, I'm waiting for the dust to settle before I jump on. I think your idea is an excellent one for a couple of reasons. I too think that slight pressure would be beneficial not harmful. I think there may be more than 2 lbs of pressure sometimes in the tank when I open the cap, so I don't see how it could be harmful. Slight pressure would prevent any fuel couplings from drawing air into the system and would prevent any out-gassing if there is any. The low cracking pressure valve is your "Eureka" idea IMHO though. It should keep the Mega filter always air-free and do double duty as a fuel pressure regulator. So far the simplest solution any one has come up with. :cool:

[jbplock]

Dave,

I missed your point (thanks A64) about the cracking valve on the bleeder. Is this to regulate/limit the pressure on the OE pump when the lift pump is running? Good idea! However, it may not be necessary (?) as there is (according to the Helms) an orifice in the OE pump that bleeds excess fuel to the return line. (If you pump up the primer and build pressure to 10 psi on the input side of the pump it will slowly bleed down as measured at the Schrader valve test port)
smile.gif

[Dave Lewis]

Bill,
The pupose of the low cracking pressure check valve is to continuosly supply the existing lift pump with 1-2 psi. The only possible problem this may introduce is if the existing pump seals were designed to operate in "vacuum mode". However, I have never seen a vane pump with these types of seals, but you never know. Another benefit of the pump and check valve would be that even as the filters started getting dirty the engine would still see the 1-2 psi up to the point the pump could no longer push through the dirty filters. When I designed equipment that used a high pressure water pump we filtered the water in 4 steps 10,5,1,1/2 micron. While this is probably overkill for our trucks something similar that could be mounted near the tank would be ideal. It would be easy to get to and easy to remove should the truck need warranty service. I would even leave the stock filter and lines in place up on the engine. Just a thought. I haven't really looked to see how much room there is by the tank. For trucks like mine it's probably easier than some others. Does anyone have any information on the Racor RFCM? It's listed as a fuel conditioning module and has a pump and several other options built in.

[jbplock]

Dave,
Thanks for explaining your pressure regulator idea… neat! While a positive pressure should eliminate the air/vapor buildup in the mega filter, do you see any benefit to trapping the air in the system by leaving the system running with a slight (3inhg) vacuum? (assuming the air is entrained and not coming from an external leak). If we leave the air in, could it still cause problems in the high pressure side of the system?

[Dave Lewis]

Bill,
I'm not sure if the amount of entrained air naturally occuring in the fuel (assuming no leaks) would be a problem unless it was a significant percentage of the fuel. I don't think air will have as big of an effect on the high pressure pump as it will on the low pressure side. From what I have been able to find out about the injection pump, it is a piston type pump, and other than decreasing efficieny and maximum pressure I don't think the air in the fuel would have a negative effect on it. I would be more concerned about the lift pump. smile.gif

[chuntag95]

I could have sworn that there is no OE lift pump on the DMAX. There was one on the 6.5L. Did I get that right?

[hoot]

I remember a comment about what happens to the fuel once it gets compressed in the pump to 20,000+ psi.

Any minute bubbles will get dissolved into the fuel by the pressure, will it not?

And the fuel is under this great pressure all the way up until after it exits the injector.

Large amounts of accumulated air could cause a problem I agree but if adding a filter and creating enough vacuum is pulling the natural air out of suspension, the only issue is what to do with that air.

I would tend to not want to be pulling that air out of suspension. Maybe you guys should be concentrating your efforts on changing the thing that collects this air. Let it pass in fine suspension if you can. The pump will compress it back into solution.

[Dave Lewis]

Chris,
The lift pump I'm refering to is the one built into the injector pump which feeds the high pressure section. I could be wrong but everything I've read explains it that way. :confused:

[chuntag95]

Dave,
Thanks. I have just thought of it as part of the injector pump and not really a "lift" pump. Thanks for the quick clarification. :D

[a bear]

Latest and last testing.
Pressured up the entire fuel system w/ propane to 10 PSI from the tank suction to the tank return. Held pressure for a few hours. (no leaks) Pulled 12" HG vac on same componets for about 4 hours. Locked in vac. (no leaks) Purged system and ran fuel return line after cooler to tank fill port. Will run about 200 miles then check for air. This will eliminate the sender and conclude my testing on this system. If I still have some air I'm sure the rest will be from the pressure drop. (outgassing) Then will come one the following choices or maybe another.

1. Install a lift pump at the tank and set the
pressure to 0 psi (neutral) at the test
schrader valve and live with the lower fuel
quality from the 0 BTU air. Bubbles should
stay dissolved though.
2. Use a pump and 12v timer to bleed the system
every few hours through a pressure cracking
check. Another rig up but better fuel quality
for improved BTU value and NO air to the pumps.
3. Go with a different filter head and filter
that doesn't trap air but hasn't been able to
produce an acceptable analysis result.(Racor
or Stanadyne)Then again accept a reduce fuel
quality and digest the air.

Hoot,
The problem is to keep the bubbles small. They seem to grow from babies to adults in the EDU coils then continue on their journey.

[ 05-08-2003: Message edited by: a bear ]</p>

[jbplock]

Tommy, Way to go!!! :D Excellent Test Method!!! :cool: I can't wait to hear if you still have gas (in the filter). :D :D

[Manfred]

Tommy I think you are on the right track in your analysis. My experience as a hobby vintner and "Bubbly" maker was, that it takes much longer to inject and dissolve gas into a liquid, than it takes to get it out. Of course pressures, temperatures and time come into play, that's the law of physics.
We deliver the fuel under vacuuum for most of the way from the tank (fuel is the coolest and gas is dissolved near maximum for the fuel allows),to the injector pump. Vacuum in the fuel path increases from the point where the geodetic hight of the fuel in the tank (variable)equals the suction process. From an outgassing point of view only, the relative small OEM filter with a relatively high location close to the engine will warm the fuel. In the OEM design, the occurring outgassing followed closely by the increase of the fuel pressure to some 20K psi, does not allow enough time for big bubbles to be generated. With the addition of the very large Mega filter, the fuel (warmer than the tank fuel) has a relatively long time to gass out. Small bubbles become bigger ones, 'til enough air is collected to cause a fuel delivery problem to the injector pump.
I think you hit the nail on the head with your suggestions and think this is also a reason, why the add-on filters, pre-OEM near the fuel cooler on the truck frame don't have this problem. They probably operate close or near a positive pressure.

[56Nomad]

Manfred wrote in part:

&gt;&gt;add-on filters, pre-OEM near the fuel cooler on the truck frame don't have this problem&lt;&lt;

When I first started experimenting with adding fuel filters, I mounted my
2 micron Racor on the frame near the tank. No problems with air. After
reading the comments on the TDP from some of the really knowable members
I decided to move the filter assembly to under the airbox post OEM, the same
location as the Mega. I still trap no air. Hoot now has the same set up and he
traps no air. With my photos is outlined why post-OEM seems more appropriate and effective than
pre-OEM fuel filtration.

[a bear]

Manfred,
Excellant and correct explanation. I agree with every aspect 100%. Temp, Vac, fuel height, and exposure time are all factors.

56 Nomad,
Adding the Racor will give you more retention time for air to break out but with your filter design you would never see it......

[Kennedy]

I haven't had a whole lot of time to spend on this, but one KEY finding that I had was that the aerated return fuel was being drawn into the pickup as the OE system is like drinking fronm a toilet wit a straw while filling it :eek:

Problem is, it appears as though we NEED to return this fuel to this cup to keep it full at lower tank levels.

The heat of the engine/pump etc, and pressure drop from HP to return fuel lines seems to aerate the fuel in the return system...

Tommy's return re-route will help shed some light on this...

[Manfred]

Nomad - If I'm not mistaken, your filter has a smaller volume than the Mega filter, thus the fuel has less time to "exhale" air. Would the difference in the fuel filter size (volume) be the problem to create the air-locks?

I would like to keep the system as simple as possible. If the injectors can handle minute amounts of gas as the OEM setup obviously does, changing a smaller add on filter more often may be the better alternative.

I like the Mega filter and it's filtering performance and hope that the DMAX-pioneers working on it here, will come up with a simple solution.

As an old Newbie, I had a slow start here with everything going well and enjoying the rig. This looks like a "boner" and I follow the experts progress daily. You got my attention! Thanks for your effort guys!

[56Nomad]

Manfred,

I have no idea whether or not the smaller size of the Racor
filter makes the difference. I wonder if cranking on the
tighening of MEGA filter will correct the issue of those with air
problems as Greg and George have suggested. That really would
be great news and solve most everyone's problems.

[chuntag95]

Manfred,
I hope to answer your question by putting an air trap before my Mega. I have one on the bleed valve and will put one post. If the air is all coming in, then my bleed valve sight glass will stay full of fuel and my pre will fill up with air. If the air is outgassing from the fuel, I will see air in both. My hope is to not see any in the post trap. It will stay there for a while to see if the system goes to some air equilibrium.
I really like this type of work. To bad it doesn't pay well. ;) I have yet to find a DMAX troubleshooting position in the paper. tongue.gif

[a bear]

56Nomad,
I also posted a while back about the importance about tightening the filters well. There were previous posts about problems breaking the OEM filter then the replies came in to hand tighten only because no leaks were seen after hand tightening. This concerns me.

[Kennedy]

If we see air at the EDU, then it is in there well before either filter system...

[a bear]

Pinehill, You've got mail

[a bear]

For those who are interested this is a follow up to my post 5/8/03.
After my last and final test (monitoring the return to the tank by clear hose) I noticed the occasional bubble passing through the hose while running. The part that alarmed me was that when the truck is shut down for a length of time then restarted there is a momentary surge of free bubbles. The longer shut down the more bubbles. This leads me to believe that we are outgassing after shut down due to the increased heat on the filters from lack of fuel flow plus the continued vac on every filter and line envolved that is above the present level in the tank. Highest being the worst. My theory on the no starts is that once the air accumulates in the Mega filter to where it reaches the bottom of the extended nipple and then the truck is shut down for (time) the vac drops only to what is required to keep the fuel in suspension above the tank level. The fuel then continues to out gas in the filters, especially the OEM which is now getting hot from lack of flow. Due to the vac drop from not running the engine the air pocket in the mega filter shrinks to make room for more bubbles above the bottom of the nipple. Then when the truck is started the greater vac is applied and the air volume grows back and then lets the extra air that is now in the system from continued outgassing rush under the nipple in one gulp therefore killing the engine.
The bad part is that by adding ANY filter under the hood above the level of the fuel in the tank and exposed to heat/vac the same outgassing is probably happening. Probably aggravated by the drop in vac from the add on plus just having more volume above the level of the tank to out gas. The reason most other filters probably don't cause a no start is probably because the air spreads out by not being able to trap air in volume in one spot. Never the less I feel confident the air is there. After cutting open the OEM filter it appears that air collects on the dirty side and is probably reducing the efficiency. Just seems that the lower part of the element is the only part getting dirty. (Could the upper part be seeing air ??)
With all this in mind it was then that I decided to go with option one of three in my previous post.

Installation of lift pump with bypass:
After discussing all this with JK he was confident of the possible outcome and offered me a pump with connections for experimental purposes and to keep. Thanks John. Talking with Pinehill also brought fourth the idea of using a bypass to control pressure and give another port of flow to the engine to keep you rolling should the pump go bad.(fail safe) Another plus to this regulating valve is that you can set the pressure to 0 psi disch to remove vac without applying pressure. Also the lift pump componets should last longer due to reduced load on the parts.
After setting the pump to maintain 1 PSI at the level of the schrader connection. Ran the engine from 600 to 3000 RPM and my first good luck came true as the pressure stayed at 1 PSI. Ran up some miles on the truck and found no air build up. Not a drop. I have since then dropped the pressure to 0 PSI and will check again tomorrow.
A pic of the install will follow as soon as I can figure out how to set it up on the net. :D :D :D
Later,

[a bear]

This is the address for the install. Hope it works.

http://photos.yahoo.com/abear112962

[Dave Lewis]

a bear,
Great explaination. Great idea. I was thinking along the same lines but to use the pressure regulator up near the engine. That way the filters will last longer because they will be seeing a higher pressure which will force the fuel to use all of the filter not just the easiest path. Does anybody have any pictures of the sending unit? I know JK had his out but did you take any pictures of it? I would like to see the cup you are talking about. I tried to look at one at the dealer but they didn't have one.
A bear the link for your pictures worked but there are no pictures in it.

[ 05-20-2003: Message edited by: Dave Lewis ]</p>

[earniem]

I have read this forum with a vengance. You guys say you have air in your system. Does it cause your truck to not start? Well I am still having that problem. The fuel tank has been replaced, The entire injector pump has been replaced the check valve on the pump has been replaced. Now it is getting worse. My Dealer is pulling his hair out. The district Engineer. Was here and checked it out and could not repeat. I drive about 124 150 miles without shutting down and about every secound time it wont start without priming it. The truck runs great but with 10000 miles on it and in the shop every month I am getting real frustrated. I ned help from you fellows. I dont want to lemon my truck. One time it did not want to run unless I kept the rpms at 1500-2000 and pumped the throttle for about 2 min. Next they plan to change out the fuel Managment system. Filter and hoses and the sending unit in the tank. Tell me they are doing the right thing

[dieseldealer]

our dealership had a truck with a similiar problem as yours. 100%stock and every so often the truck would crank and not start. pump the primer and it would start. it happened every once in a while. our dealership replaced all fuel system components from tank to engine,filter housing and a few other parts. this truck could not be repaired and the customer is now driving a 2003. his previous truck a 2002 was bought back by gm.

[Idle_Chatter]

Sorry a-bear, but "your album is empty" at that link. Are you sure that you selected "share with the public" for those photos? Also, Yahoo just recently decided that you *can't* share your photos unless you pony up for the "Deluxe" version of you briefcase for $10 a month conveniently charged to your credit card! :( I use my briefcase a lot, and I pay the tariff :mad:

[jbplock]

Tommy,

Great Work!! :D :D :D (you have mail)

I'll be installing a pressure regulated lift pump per your design ASAP! :cool:

[ 05-21-2003: Message edited by: jbplock ]</p>

[a bear]

Thanks guys.
Try this


http://community.webshots.com/user/abear130

[Kennedy]

I guess the next step would be to set up some fittings to convert to hose barb and allow NPT "tapoffs" for a bypass loop.

Either that or just run it at the 5psi generated. The major concern being if the pump stalled as it adds about 2"hg restriction.

[Idle_Chatter]

Great installation, Tommy. Unfortunately, I have my 6-way fuel tank valve mounted in that very position (on the two holes you see in the frame rail just behind your pump). I do have the line already cut, so I guess I could go further forward up the frame if I went this way. I'm very interested in the pressure regulator installation and a parts list would be great! Once again, good job and thanks for the information.

[a bear]

Idle_Chatter,
All I used to regulate pressure is a $4.95 1/4" NPT needle valve. I went this route to provide an additional flow port should the pump go out. It works great with this and there was no drift in pressure setting at all RPM ranges. I presently have mine set at 0 PSI @ the schrader valve. No vac or pressure. This is a list of the materials I used and I also added a few more pics to view at the below web page.
If JK is looking into putting a fitting kit together which I think he may be that would probably be the way to go. It would probably save you a lot of connections, running around and would probably look more custom.

This is what I used.

(4) 1/2" hose clamps
7/16" fuel hose (for a tight fit)
(2) 1/4" NPT x 1/2" barbed hose fittings
(2) 1/4" NPT Tees
(3) 1/4" NPT x 3/8" tube fitting(compression)
(1) Flow through type fuel pump
(1) Street 90 deg
(1) 1/4" all thread nipple
(1) 1/4" needle valve
(1) 1/4" NPT x 3/8"tube 90 deg
(1) small length of 3/8" tubing (comes on fuel
connects)
(4) Conduit hangers
(4) 1/4" x 1-1/2" ss bolts
(4) 1/4" x 1/2" ss bolts
(8) 1/4" lock nuts
(4) rubber bumpers
(1) oil pressure switch (pressure to close)
(1) 3/8" x 1/4" bushing (to mount switch)
(1) roll of black poly loom (to protect wires)
(1) Weather tight fuse holder(1st item at power
supply.
(1) Sealed GM two prong plug for pump.
Misc. electrical connectors
Optional- 12v switch to turn on pump manually for
priming.


http://community.webshots.com/user/abear130

[ 05-21-2003: Message edited by: a bear ]</p>

[jbplock]

Tommy,

Thanks for posting the additional pictures and parts list! Very professional install!! :D

I ordered an AC DELCO lift pump (6.5TD version, like the one you used) from JK yesterday. I’ll be retiring my bleeder pump since it’s not up to the lift pump task (I guess I’ll keep it around for use as a power siphon). I’m also thinking about installing a filter in front of the lift pump. These pumps are known to fail at about 50-60ki miles on the 6.5 (it failed on my 98 at 60kmi). There was some discussion a few years ago on the forum that the premature lift pump problems were caused by dirty fuel. In fact, I believe Autozone gives a LLT warranty on the pumps they sell only if a filter is installed in front of the pump. I was looking at either the RACOR 645 or Stanadyne FM100 with a 10 or 30 micron element. Also, where did you get the Oil pressure switch you used? Did you also use a relay between the switch and the pump. I believe the early 6.5 OP switches were wired direct to the pump and they were prone to failure (due to the inductive current load of the pump) . The later ones used a relay. I was also thinking of rigging a delay to run the pump when first starting the engine before the Oil pressure comes up. Maybe even a fuel vac/pressure sensor with a gauge in the cab to monitor that the pump is working. Any thoughts on all this? (I’m given to overkill so somebody reel me in if I’m going off he deep end). :eek:

[ 05-22-2003: Message edited by: jbplock ]</p>

[hoot]

-----------stutzismydog posted------------
Hoot~
I here what you are saying about making the OEM filterer obsolete if a PER-OEM filter is installed. Just think of it as EXTRA PROTECTION.

The point I was trying to make.....is to give GM engineers some credit and not mess with their design by putting a second system POST-OEM in the fuel flow, it looks like it is causing problems.
----------------------------------------

stutzismydog,

If we gave GM engineers some credit, we wouldn't be installing any filters.

As far as messing with the design, wether you go pre or post, you are messing with it.

And lastly,

Who is having problems?


a bear,

That is a work of art. Beautiful install.
Just be aware those hoseclamped rubber connections can leak air without a raised rib in the steel line.

That should reduce vacuum in the lines in front of the two filters which should minimize air being pulled out of solution but it does not eliminate dissolved or entrained air introduced by the system. It mearly holds it in check and probably allows you to run a 2 micron for a longer period of time.

[ 05-22-2003: Message edited by: hoot ]</p>

[CntrlCalDmax]

jbplock ,

Since you are thinking of running a Stanadyne FM100, why not run there optional filter with lift pump? The fuel flows through the filter prior to the pump for pump protection.

a bear,

I have a pressure gauge installed in the cab and monitor pressure pre OEM filter. I use a manually adjustable bypass orifice like you did. The pressure does not change at different RPMs with no load, but on the road, I find pressure will drop about 3-4 psi from no throttle to WOT, especially noticable when towing.

Leo

[ 05-22-2003: Message edited by: CntrlCalDmax ]</p>

[a bear]

Bill,
The switch is a NAPA BALKAMP 701-1575 ($27 + tax)
I am presently wired directly through the switch with a manual on switch for priming which also overides the pressure switch. I have tried this without the relay due to the reduced load/amp draw on the pump @ 0 PSI. I like the short delay while waiting for oil pressure to build because it gives the pump a soft start with less peak amp draw. Im thinking the pump and switch will last a long time under these conditions.

Hoot,
Thanks. I have the 7/16" hose connected to hose barbs on the pump side then stretched over the 1/2" tubing w/clamps. Thats why I use this instead of the 1/2" size. Holds like a champ. Besides I still have the bonus air trap on the Mega that will alert me to any possible future air problems. :D :D
I'm not real concerned about the naturally occuring air in solution as it doesn't cause problems. As long as we can keep those free air bubbles in check we are well ahead of the game. :D :D
Like those riv nut pics. Did you use the Macro setting. I will have to get used to my new toy I guess.

[Kennedy]

Keep in mind that Tommy's setup is an experimental prototype and that the future should yield a significantly shorter parts list along with less fittings.

[hoot]

Yea I used the macro setting. It's a Nikon 990. The macro allows you to get as close as almost 3/4 "

John,

Will you be offering something similar in kit form in the near future? I may be interested.

[ 05-22-2003: Message edited by: hoot ]</p>

[Rebel_Horseman]

If this is what it takes to get my fuel system and therefore motor to last longer, then I would definately be interested as well.

Reb [&gt;&lt;]

[a bear]

Leo,
OK you had me worried so I just ran out hooked up the gauge, slipped it under the windshield wiper-Sorry John and ran the snot out of it on my local 4 lane. Radar detector on and needle buried and turbo raising the hare on my back. The pressure stayed the same as set @ 0 PSI. I am waiting on a phone call them will go out back to hook up to the cattle trailer.(before lunch) and check again. I guess at this point I am wondering about any difference in our pumps. :eek:
Seems that by returning the larger percentage of our fuel we should only see a drop in return flow while loaded while the engine burns the increased balance.

[jbplock]

Leo,

I thought about using the FM100 with it's built-in lift pump, but my understanding is that it's not a flow through design like the 6.5 lift pump.

Tommy,

Thanks for the OP switch info. Regarding the relay, your probably ok. The only other point to consider is that the pump is an inductive load, which when switched on and off, can stress the switch contacts (if they aren't designed for it). I'll see if I can find some specs on the OP switch you listed.

smile.gif

[ 05-22-2003: Message edited by: jbplock ]</p>

[CntrlCalDmax]

Tommy,

If you have a chance, set your pressure to something positive, even 1 psi and try it loaded again. I sure would like to know if my setup is responding abnormally.

Leo

[a bear]

Leo,
I tried setting the pressure at 2 PSI and ran at full throddle with the trailer and the pressure stayed where set. Set it back at zero and again it stayed at zero under load. I passed this guy driving a PSD and you should have seen the look on his face. Definitely a Kodak moment. :D :D
One thing I did notice is that it seems to be pulling stronger. The pressure drop you are seeing must be a difference in the pump.

[chuntag95]

Tommy,
Where did you put the switch, the port at the filter?
Chris

[jbplock]

Chris,

Tommy updated his pictures to include the switch install as follows:
http://community.webshots.com/photo/73924877/73958789MvqCnW

From the picture it looks like he also has his bypass feed (?) installed on the bottom port of the oil cooler/filter adapter.

I'll probably mount the OP switch with a tee at the inlet to my OilGuard Bypass filter.

smile.gif

[ 05-22-2003: Message edited by: jbplock ]</p>

[CntrlCalDmax]

Tommy,

Thanks for the information. I will have to do some more testing.

Leo

[chuntag95]

I see. I can put mine on the back of my Amsoil bypass as well. A nice clean run down the frame rail for the wires. Now all I have to do is buy the switch, pump and other stuff.

[CntrlCalDmax]

FWIW, I used an aircraft oil pressure switch for my fuel pump. On the aircraft we see 100 psi on startup so these switches should be fine with our higher oil pressure. I have not been able to find a current rating spec. but they are used to run devices in the 5 amp range. They are $16.23 and are in stock.

Leo

[jbplock]

Leo,

The aircraft OP switch sounds good! Could you post a part number and supplier?

Also, what type of fuel pressure gauge are you using in the cab? Thanks! smile.gif

[ 05-22-2003: Message edited by: jbplock ]</p>

[a bear]

Bill,Chris,
I did use a separate port to mount the oil pressure switch. Don't know why. I guess because it was there. :D The reason I terminated where I did under the hood was to keep as chris said one neat little run. Only one small branch to catch the oil pressure switch. Does anyone know what size fuse I should be running for the pump? I have a 25 amp in there now and I'm sure I can go much smaller. Bill, Do you have a part # and location for the relay. I'll keep one on the shelf just in case.

Leo,
I'd like to second that motion for the switch PN. :D :D

[jbplock]

Tommy,

I started researching the relay’s a little today but haven’t picked one yet. I’d like to find one that’s weather proof so it can be mounted under the truck, other wise I’ll probably look for a place under the hood. I’m also looking for a relay with a built in adjustable delay. I’ll post all the details once I get them worked out. It may take me a while though (Like JK said my other (non-truck) life is getting pretty busy with the onset of summer) Regarding the fuse, I would think a 5amp would work. This is what I used on the bleeder pump (which is very similar to your AC Delco pump). I also found a neat weather pack fuse holder at Tractor supply. I’ll take a picture and post it when I get a chance (hopefully tomorrow). It has a mounting tab that I attached to the side of the fuse box under the hood. I ran one side to the open “B+” terminal in the fuse box (under the hood) and the other side to my pushbutton switch under (also under the hood). I’ll probably adapt this to the new lift pump.
smile.gif

[CntrlCalDmax]

I don't want to get in trouble with the mods, but here is the oil pressure switch information.

Part number S3010-1, $16.23, 4 in stock and can get plenty more in 1 day.

Drop me an e-mail leot@corpair.com

The fuel gauge I use is a 0-15 psi 2.5 inch analog gauge temporarly mounted behind the console to the right of the throttle pedal. As soon as I am done with fuel system mods I will take it out. I just haven't found a suitable location for a permenent gauge. I'm thinking of adding another transducer for the Xmonitor and switching between exhaust brake back pressure and fuel boost pressure.

Leo

[ 05-22-2003: Message edited by: CntrlCalDmax ]</p>

[jbplock]

I posted some pictures of the fuse holder and switch location for my bleeder pump. I'll probably keep these when I switch to the lift pump. Click on the JK_megafilter link in my sig (they are on the second page) smile.gif

[ 05-23-2003: Message edited by: jbplock ]</p>

[chuntag95]

Bill, nice catch bottle. Where did you get that idea? tongue.gif :D

[jbplock]

Chris,
Yes your bottle idea is working great. :D It will make the gas tolerable until I get the lift pump installed. I ordered my pump from JK earlier this week and it's here today (Thanks John!). I found the "bump tube" I need to connect the pump in the Napa catalog. Hopefully my local Napa will have the parts.

Tommy,
I looked up the switch you are using in the Napa catalog and Hobbs (a division of Honeywell) makes it. The Napa catalog says it's rated for a max pressure of 150 psi but does not give electrical specs. It's listed as an accessory for hour meters. I think I found the same switch at the Hobbs site but the Hobbs PN's are different than the Napa numbers. It lists an inductive load rating of 1 amp at 120VAC but not for 12VDC. The link is as follows: http://content.honeywell.com/sensing/hss/hobbscorp/catswitch4.asp
Currently, I’m planning on using Leo’s switch with a relay, hopefully with some sort of delay.

The Hobbs site also lists some Vacuum switches that could be used on the fuel line to sense if the lift pump has stopped working... Maybe turn on a warning light if the vaccum drops below 2inhg (??). Something to think about.

smile.gif

[ 05-23-2003: Message edited by: jbplock ]</p>

[a bear]

Bill,
Thanks for the info. That looks like the switch. It should come close to 10 amps for 12V service. The vac switch sounds like a great idea. Zero air @ zero Psi by the way. It sure seems to be running smoother/quieter. :D :D :D
Just posted pics of the last two OEM fuel filters cut open for a base line. Curious to see if the element will dirty up evenly now that its definitely fluid packed.

[ 05-23-2003: Message edited by: a bear ]</p>

[Dave Lewis]

I'm curious. The people that have installed the lift pump do you still get air in the mega filter but it just doesn't cause a no start or stall? If you were to open your bleeder do you get all fluid or does it still release some vapor? The reason I'm curious is that I wonder if it is still able to trap the entrained air while being pressurized or is the air now staying in solution? Sure would be nice to have everything, less air, clean fuel, always starts.

[a bear]

Dave,
I am currently running the lift pump to remove vac only(set @ 0 psig after the filters) I have ran over 600 miles since and there is no air to be found.

[ 05-26-2003: Message edited by: a bear ]</p>

[Dave Lewis]

Just a thought I had after reading some of the other posts relating to fuel problems. With several people needing to have their fuel lines replaced due to rust could this be an issue for all of us, or maybe they just have bad fuel in their area. On the machines I designed that used a high pressure water pump we used nothing but stainless for all of the lines and fittings. Now granted this was a water based fluid but with the cycling of pressure you wouldn't want any rust particles becoming dislodged and finding their way to the injectors. I haven't checked but the lines to the injectors or the manifold itself do not look like stainless. I wonder if the people having repeat injector problems have rust in their system somwhere after the pumps?? Also what's to stop the particles the pumps themselves will create over time. I guess it's a never ending quest for cleaner fuel. :eek:

[earniem]

Bear your install looks real good. Do they make that type of pump to fit 1/2' line in the 2003 truck? I dont want to sell my truck back but am getting tired of messing with the no start problem

[hoot]

I thought this was interesting.....

=========================================
Bilstein shocks utilize a mono-tube design filled with nitrogen gas and hydraulic shock oil. (A floating gas seal separates the nitrogen from the shock oil.) A nitrogen gas pressure of 360 psi is maintained on the oil column, which effectively eliminates foaming and cavitation, and maintains dampening effectiveness even on punishing road surfaces.
=========================================
From.....
http://www.thedieselpage.com/reviews/bilstein.htm

360 psi eliminates foaming and cavitation in shock oil. I know it's not the same situation in our fuel system but I wanted to continue to bring up the fact that highly pressurized fuel in the 20,000 psi range most likely will hold air in solution quite well. All of the fuel from the hp pump to the injectors is under this continuous pressure. Did I say this before? Is naturally occuring dissolved air under this amount of continuous pressure a problem?

[jbplock]

Hoot, (do you always shy away from controversy?) tongue.gif

Your make a good (reiterated) point about the air being re-dissolved in the fuel by the HP pump

[hoot]

I am only guessing that large air pockets could be a problem on the way into the high pressure portion of the pump. Unless there is something designed in to expell this air, we are talking about a rotary piston pump in the configuration of a radial engine. Some cylinders get a gulp of air while others get fuel. I read major load imbalance. I could be dead wrong. The pump may be able to handle any imbalances but that would be my guess as to where large volumes could be a problem.

I would suspect Bosch designed-in a certain amount of expected large volume air intrusions since it's likely to occur during fuel system maintenance and filter changes. Someone mentioned a factory bleed valve that is being used to measure vacuum by some. It is possible this valve is there to reduce initial assy/start time as well as to minimize air during initial startup of the engine on the assy line.

Now after the fuel has been pressurized, in a naturally occuring dissolved air situation, I believe the air is a non-issue.

The only place it could be an issue is like you said, as soon as it goes from 20,000+ psi to cylinder pressure which is a very quick drop in psi. Fortunately, this occurs in the cylinder immediately after exiting the injector. Also, cylinder pressure may not be low enough for the air to "exhale" out of the fuel, although my thinking on that is uneducated. It could be just the major pressure change that pulls it out. Anyway, I don't think it's an issue in the cylinder itself. Hey, it may even lower egt's :eek:

[ 05-29-2003: Message edited by: hoot ]</p>

[a bear]

Hoot, I'm assuming your pertaining to the bubbles getting large in the Mega filter. The bubbles are growing through the entire system. Many members including myself have reported the large pockets of air before the Mega filter. So if the Mega wasn't there guess what ????? :eek:

[a64pilot]

a bear,
Don't have much time, I have to get back to work. But I'll bite, I give up what happens, In more than 60,000 miles I have never had a stall, rough idle or loss in power or anything that could be contributed to an air in fuel issue. I know that one truck and 60,000 is nothing, but I don't think that you can get 600 out of the Mega without pressurizing the fuel system. Remember I said a long time ago that I thought the only realistic way to eliminate the air in fuel issue was to pressurize the system, I still do. I still think that air in fuel is a known issue, been engineered in and apparently is only a drivability issue with the Mega.

[Dave Lewis]

The air may not be damaging the portion of the injector that goes into the cylinder but what about the part of it that bleeds the pressure off of the servo piston? The air could come out of solution when the ball lifts off of its seat damaging it at this point. I believe the pressure at this point would be roughly atmospheric??? Having the ball damaged would allow the injector to return fuel causing the servo piston to open.

[a bear]

earniem,
All our fuel lines are presently the same 1/2" line. Unfortunately connecting from the pump to NPT fittings requires having to adapt. This takes a couple more fittings. John was looking into a fitting setup for his customers who wanted to go the lift pump route. Judging by the critical nature of a couple of our members I'm not sure where he stands on this. If you give him a call I'm sure he will be willing to help point you in the right direction. It appears we have a couple of proclaimed experts on the Mega filter who don't even own one nor took the initiative to check their own system for air.
As for the lift pump I now have it set at at about 1/2" HG under 0 PSI with no issues and holding constant. This is where it will reside.

[Kennedy]

Dave Lewis,

You are one of the first here to realize this!

Of the injectors that I have sent in for testing, one thing remains consistent: LOW DELIVERY volume. 20% low is pretty common. Some as much a 30% low. The nozzles can be swapped from injector to injector and still produce the same results. The clearance is getting loose, and more fuel is bypassing. Whether this is dirt, air, both, or a quality control/materials issue we do not know.

We are back to the reason I have been holding off on performance injectors: inconsistency. FYI, new injectors are very consistent.

[Dave Lewis]

John,
If the ball is passing more fuel wouldn't this cause the nozzle needle to lift off the seat all of the time and create basically an open nozzle?? I'm just a little confused on how this would produce lower volume on the shot. I could see it happening if it wasn't fed by a pressure pump. I'm sure I'm just missing something, how does it work in reality? Is the continuous pressure drop enough to reduce the volume of the shot?

[a bear]

Pilot,
No air and no pressure. Try again! tongue.gif

[chuntag95]

It took over 200 miles to get air through my Mega as verified by my post Mega air trap. I still saw no stalling or idle problems. I think the stalling and idle problems are caused by something else. I saw a HUGE amount of air go through my system without any stall when changing my lines out to clear. Some trucks seem to take air in stride and others don't. That is the issue that needs to be addressed for the people stalling. We and the general are missing something on this one. Several have stalling problems in stock configuration, so what's up with that? There is a leak, a vapor lock, a ???? :confused: All we need is the right person to have the problem and sort it out.

[56Nomad]

chuntag95 (Chris) wrote in part:

"Several have stalling problems in stock configuration, so what's up with that?"

Chris, maybe time for a new post to see how many are having such with air problems with
stock fuel set ups. Maybe I missed something?

[dschultz]

I have been following the secondary filtration threads for a long time now. I found an item that caused me to wonder if it would work as a vent to the trapped air in the filter. The part is a Racor Marine Fuel/Air Separator. The part is installed in a tank vent line to prevent fuel from being sent overboard when filling a tank.

I was wondering if it could serve as a air vent on a filter head port or tee. I have not been able to find out how the separator works or if it is a one way vent.

Does anybody know how it works?
Thoughts on any application as an air vent?

Thanks

Dave


I forgot to include a link to the racor page:

http://www.parker.com/parkersql/bulk.asp?body=pdf%2Easp%3FPSID%3D3071&rnd=5%2F29%2F2003+6%3**0%3**0+PM


sorry....

[ 05-29-2003: Message edited by: dschultz ]</p>

[NWDmax]

I'm one of the guys with Mega air and after thoroughly checking the system its still there.
I'll be installing a similar set up as abears set to 0 psi and report my findings.
Thanks to JK,Tommy.Chris and the rest for all the great ideas.
I've been eating and sleeping this stuff and its a blast!

Abear:Can you give a brief explanation on how the needle valve located in the bypass line works as a regulator?
Thanks again.
Blake smile.gif smile.gif :D

[a bear]

NWDmax,
The valve simply returns some of the fuel to the suction side of the pump at a pressure you select.
Once it is set it requires no further adjustment unless you choose. It is completely maintenance free and should last a long time with the reduced disch head. I was pleased that the pressure stays as set under all RPM and load ranges. Also I have recently noted a 30 mile increase in fuel mileage per tank with a smoother/quieter engine. it is also fail safe should the pump go out and can be used to prime filters when changing. I have recently adjusted the pressure to -1/2"hg with no issues. I can honestly say that I have found no faults in it since installed. I am going to my sons graduation tonight so if you or anyone else has a question I will be returning tommorrow and would be glad to help. smile.gif

[NWDmax]

Thanks Abear,kinda thought that was it but wanted to be sure.
I've got this thing sitting on my desk at work and trying to give a brief explanation of what it is/does and why is tough.
Have fun at graduation I've got a daughter who is doing the same on June 6th.
Blake :cool:

[jbplock]

FYI … to those implementing Tommy’s lift pump enhancement.

I just ordered a Stanadyne FM100 30-micron pre filter from ReliableIndustries.com that I plan to plumb in front of the AC Delco lift pump (to protect the pump).
http://www.reliableindustries.com/inv/stan/assyinfo.php?search_for=33641
http://www.stanadyne.com/dsg/dsg_dffs.asp
My experience (as well as others) with these pumps on the 6.5L TD says they fail at about 60kmi. It was suggested in past discussions on the 6.5 forums that a pre-filter could prolong their life. The cool thing about the FM100 is that is has two input fittings. I'm planning to connect the pump input directly to the filter output and then plumb the bypass return (with hose) to the second filter input, which will save a few fittings. (I ran this by Tommy and he gave me a thumbs up). It may take me few weeks to get this hooked up (life is busy right now), but I’ll post pics and a complete description when I get it running.

smile.gif

[a64pilot]

a bear,
Yes it is under pressure. Usually around 14.7psi. By under pressure I guess I should have more accurately said not allow a pressure less than atmospheric. It's the release of pressure that is causing the air to come out of solution, kind of like when you open a bottle of soda. So when you are keeping O psig you are really around 14.7psia. Either way by not allowing a pressure drop you are not allowing the air to come out of solution and if you had any leaking quick disconnects under a vacuum they will probably not leak under atmospheric pressure.