Fuel pump help

Hi Casey
Had a similar problem on my skidder,would run great for about 1/2 hour then begine to lose power till it would bearly idle.Change filter all was good for the same time,over and over.Turned out to be a bunch of stuff in a brass elbow.It would slowley plug the elbow as it was running.Shut it off and it would begin to slowly sink down stream.
I found the problem by using a jerrycan as a fuel tank,hooked it up and the skidder ran great for hours,had better power too.Previous owner had just changed the injection pump chasing fuel problems till he busted the tranny.He mentioned the new pump,but failed to mention the ongoing stalling.
Good Luck
Thomas

Last night I took everything loose from the lift pump forward. I completely removed the filter housing and found a layer of what I would call 'tar' down in the bottom. It was some nasty stuff. I guess 240K miles and years of differing kinds of fuels had taken its toll on it. I completely disassembled the housing and thoroughly cleaned it and put it back on.

I also blew air backwards from the hose connected to the inlet of the fuel filter back to the disconnected hard line going to the lift pump. Surprisingly little debris came out. It seemed to have really good air flow, so I buttoned everything back together to see if anything changed. I appeared to have better flow to and from the filter, so I drove it to work this morning, or should I say, attempted to drive to work.

I made it about 6 miles down the road before she started sputtering again. Pulled over, popped the hood, and checked the filter...no fuel at bleeder valve. Had to run the pump quite a bit before a trickle of fuel finally came out the top of the filter. Decided to turn around and head back home. Long story short, tried bleeding the filter several times, and got within 3 miles of home, and ended up calling for a tow back to my house. I couldn't even keep enough fuel up to the engine to keep it running.

Haven't checked anything else yet, but the problem is getting worse and worse which means I HAVE to be able to pinpoint the issue!!

Next up on the list is checking the suction of the pump (again) for restrictions. If that doesn't turn up anything, I'm going to try running a few miles on an aux tank and bypass the main tank.

It seems to be that when sitting still and after sitting overnight, the pump works great. After driving a few miles, it's like something is shaking loose and restricting the flow of fuel. It's rather frustrating to keep running out of fuel when there is plenty in the tank!!

I'm hoping to get it running again and drive it a bit until it quits, and then immediately see if I can tell where the restriction is...suction or pressure side of the pump. So far, by the time I'm able to work on it, everything is back to normal. Now I need to try to catch it in the act, so to speak.

Casey

Air leak between the fuel in the tank and the LP,or a clogged fuel sock on the sending unit,or a plugged vent in the fuel cap are the most likely cause of your problems.

Without re-reading your whole post could you let us know how you power the LP when bleeding?

Have you opened the WIF Tee-valve when the engine idles to ensure the LP is pumping while the engine runs?

you could try to connect a container of fuel to your lift pump to take the tank out of the equation....it sounds like since youve lost your fuel at the filter that youre either pulling air before the lift pump or have a blockage in the tank /cap/fuel filter or lines (which will also pull air thro' joints you thought were tight) hence no fuel at the filter.the F.i.P'S trying to deliver it but theres little or none coming to the pump.go back to basics before you hit your wallet ....achems razor(?) it is often the simplest thing at fault.start with the cheapest things to diagnose...I'm thinking old skool here tho' and with a miriad of electronics 'making your day' it makes the diagnostic process harder. start with the basics first tho' and then go on to prove your lift pump on the move with a fuel pressure guage tee'd in.after proving tank/pump filter youre firmly in electronic pumpandwiringland ... and there are a wealth of brains here to help you out.
i once had a garbage truck with a similar intermittent run/stop problem...pointed to the fuel system but where to start..i eventually worked my way BACK to the fuel tank (so i would START there first) and found a pvc workmans glove in the fuel tank....they had just fired one of the ops that morning coincidently. he got his own back.aint life great... :¬)

After reading this article:

http://www.thedieselpage.com/members...s/model80c.htm

I have come to the realization that there is no screen at all in my filter housing. I don't think I've ever seen one in there. So I need to remedy that. I have read that several people go with a Racor filter setup. Any recommendations?

I also found this article:

http://www.thedieselpage.com/members...eturnflowc.htm

This sounds very similar to what I am experiencing. I noticed, in my opinion, what was a large amount of fuel being pumped out of the return system of my IP. I'm starting to think that excessive fuel return could be part of this ongoing issue.

My SES light has been disabled. What is the next best way to read codes (1995 model)? Or would it be simpler to fix the SES light? I believe I am having serious injection pump problems now. She won't run without blowing tons of smoke and shaking terribly....like the timing is way off. I'm pretty sure the IP is toast, but I want to pull some codes and do a good job of diagnostics before I start replacing parts.

Thanks,

Casey

Hello RVTEC;

I have the exact same problem, I mean exact same and have done exaxctly what you have done, and I have finally given up after almost two years and brought it to a garage. They have had it for three days and now say it is the lift pump. I told them that I have changed it multiple times, but what the heck, let them try it.
One thing that I have found is that these lift pumps do not like to self prime, ie a little air in them and they just do not pump.
About a year ago, I fixed the problem for about three months by cleaning off dual battery terminals because lift pump was getting low voltage. Makes me think that these pumps are very sensitive to voltage, and while driving, start and stop pumping, get an "air lock" and then stop pumping. Only thing that I can think of.
This is so weird, I could have written your exact postings.
1997, 2500 Subway, 200 K miles.
Regards,
Wayne

Hello Again:

The more that I think about it the more sense it makes. Voltage to pump drops lower for a bit and pump stops pumping but may still make noise. Somehow gets some air in it, maybe from on/off pumping and then will not prime. May overheat, thus sometimes requiring the truck to rest a little before it will work again.
I don't know, just guessing, as this has been driving me crazy for years.........

I did try jumping the relay so pump would run allways, but no change, thus this may not be the problem. I have tried everything.

Regards,

Wayne

I hope you get yours figured out, Wayne. Let us know what happens.

In the meantime, my rig is down for the count. She won't even drive now. I'm waiting for some more time to run some diagnostics, but everything is pointing to a failing injection pump. She'll start and run, but she'll blow tons of smoke and shake the whole truck badly. The timing is all over the place. I'm thinking the optical encoder sensor may have died again. And this may be a result of poor fuel delivery over the past few months.

I went ahead and ordered a Racor fuel filter setup yesterday. I'll get that installed and then move from there. I am definitely not pleased with the factory fuel manager system. If I end replacing the IP, I want to make sure the new one has a steady source of clean fuel.

Casey

Hello RV:

Please let me know how it works out with yours. I hear that letting the IP pull all the fuel instead of the LP is bad for it??

I have not heard anything from the garage today so I bet the new LP is not any better, like I told them.

I do know that when the LP was working, the overall performance of the truck was much improved.he

I went through two IPs under warranty, and after the third failed I replaced the driver with one on a heat sink and so far so good after 50 or so k.

Keep me posted and good luck.

Regards,

Wayne

The lift pump should have no problem priming itself.

It also should not get air in itself unless the fuel level in the tank falls low enough to allow air into the pickup. If it does, then there's a leak somewhere between the pickup and the pump.

If it's clicking it has enough voltage to pump. It only clicks when the spring inside has forced the fuel down the line. The click is the "intake" stroke of the pump. The spring provides the pressure. If it clicks and doesn't pump then it may have air in it or the check valves may have failed.

Its an expensive misdiagnosis to replace an injection pump only to find your fault is still with you.....

I would try all of these first:-

remove/clean the fuel tank/sock (mine stood for a year and was full of brown crud/bio-organism that grows in water /diesel)
blow out all the fuel lines from ip back...
ensure fuel cap breathes..
test pump itself using 12v supply and 'suction' pipe dipped in fuel container....make sure it flows fuel from one container to another..not worried about pressure just yet..
fit new filter and prime system using a vacuum pump at the water in fuel drain point(after your little tap on the thermo hsg)
crack off 3 or 4 injector nuts that you can reach easily
get someone else to crank/start engine while you look at injectors that have been cracked...
shut it down/stop cranking when you can see fip 'spurting'a little fuel from the cracked open ends..
fit a fuel pressure guage to that drain line (extend it if you want so you can see it from driving position)
retighten and start engine....if engine wont run try partially clamping the fuel return line at the ip but leave it with some flow....ive read about people suffering what they think is excesive fuel return flow but cant understand why (or is there , experts help me out here) there isnt a fuel restrictor in the return line to keep the fuel pressure up at the ip within tolerance range (i know overpressuring it affects timing)
I'd rather chuck some money at a few cheap diagnostic tools ie guage/fuel line/spare pmd than a lump of cash at the wrong thing...if youre satisfied youve done all you can i'd ask a diesel specialist who knows these engines to diagnose it as well....

if youve got a spare pmd (should be remote mounted behind bumper) fit it in place of yours...
repair your ses light (best indicator of fault) follow procedure in 'the diesel page' for jumping terminals to read off the flashes.

if it wont run at all check your harmonic balancer is serviceable and get someone to hold the ring gear (remove starter)with a screwdriver while you turn the crank from the front to check if its broken.

mech injection pumps usually wear out slowly over a period or some linkage gives out inside the pump but these solenoid controlled ones present extra diagnostic problems... i dont envy you...good luck tho'

Hello All;

End of saga I hope. The diesel mechanic tried everything, including new lift pump. No change.

Finally after pulling the tank they noticed that the pickup sock was clogged up a bit, then they noticed that there was no check valve pickup to bypass the filter when it was clogged. Then they realized that the sender unit in the tank was for a gasser and not a diesel, so the sock was much finer and no check valve when clogged.
They removed the sock and now no problem.
All out there with this problem, check to see if the sock is clogged and if it is the correct sender unit, gas ones are different!!!!!

Now, is it ok to run without the sock???? as they did not want to replace the whole unit??

I seriously dislike auto parts places that are not carefull in what they supply.

Regards,

Wayne

I have read about the check valve bypass, but neither the new pickup assembly I purchased nor the original OEM unit had one.

I would think that a gasoline assembly would not have the correct fittings. Also, the gasoline rigs of the same vintage trucks had the fuel pumps inside the tank. So, I doubt your pickup assembly was actually made for a gas rig.

I believe that some of the pickup assemblies had the bypass, some didn't.

Casey

It seems as though some aftermarket suppliers use the same fuel sock for both gas and diesel sending units to cut costs/inventory-the result is a poor performing product.

This is too strange. The diesel mechanic said the strainer was definitely from a gasser as he compared it with one from a diesel and said it was much coarser.
What do you all think about running without a strainer to eliminate this nonsense, and just change filters more often???
I would have thpought that the gas unit wouold have been much different also, so must be the wrong strainer issue???
Regards,

Wayne

I would remove the strainer completely and then add an inline filter before the LP.

Dorman makes short fittings with the proper fitting for the LP and sending unit with a hose barb to allow diesel rated neoprene line to be run between them,get that at most parts stores and then add the inline filter where it fits good for changing.

fitting for example only:
http://www.dormanproducts.com/carque...2-800-240.aspx

This thread http://www.thedieselpageforums.com/t...ad.php?t=39905

might give you an idea for an alternative fuel filter,.and an alternative fuel
pump,.

http://i39.photobucket.com/albums/e1...g?t=1324163476

http://i39.photobucket.com/albums/e1...g?t=1323563124

Nick

Ill try and get some pics on the set up i run on my 94 burb tomorrow for an idea

Mechanic said that the filter sock had some waxy tan stuff clogging it. Tank and filter were otherwise clean. Truck is running beter than it has for several years.
Will keep an eye on the main filter.
So far so good. This has been a major pain over the last several years and finally seems to have been solved.
Regards,
Wayne

The sock is not the problem. Ever. If it's plugging up, you have fuel quality problems, regardless of the screen size. I've seen them in various sizes, OEM and aftermarket, model to model and year to year. They are all sufficient to do what they need to do. It's there for a reason, and it sounds like it did its job (Wayne). Your tank and fuel may be "otherwise" clean, but it apparently wasn't always. Removing it defeats the fuel system's first line of defense. A pre-pump filter is not a bad idea, but it doesn't replace the sock. A "mechanic" who removes the sock (to "fix" the problem), because it's fouled, is no mechanic.