03 rpm's fluxuating,hesitating, stalling...need help

[tammybrian2]

a few days ago my truck seem to be hesitating a little, but would run fine on highway. i found a pinhole in a return fuel line that runs from top of fuel cooler back to tank. for the time being i cut out the bad piece of line and replaced with hose. I also changed the fuel filter as well. filter filled with fuel when priming. once that was done, i had a hard time getting truck started again, (it would start/run for about 30 seconds or so then stall) trying to get any air out of the lines. as i primed the fuel filter, i was pumping a lot of air. the primer is working ok, if i pump fast enough, maybe 2 pumps per second, the air bubble would stop as the filter would fill completly with fuel and only spray out fuel, except i could never get the primer so hard that i could not push it, i could just keep pumping. then what i tried was prime the filter then turn the key to the run position thinking i was basically 'priming' the injectors/fuel system (but i could be wrong about that). i did this three times, prime the filter, turn the key to 'on' and keep priming, then turn key off, prime, turn key on, keep priming filter etc. the last time i did this, i started the truck, as the truck ran, i continued priming, this time the truck continued to run. i stopped priming the filter, and the truck continued running. i let it idle for about fifteen minutes or so then took it up/down the road a couple of times with no issue. after the short drive, i was then able to prime the filter to the point i could no longer pump. i also noticed the rpm's fluxuating at idle, while it was hard to see any change in the rpm needle, i could hear it.
i also had three codes come up: P0571, U1041, U1024. i cleared those codes (since the truck was running again) to see if they would come back. U1024 was the only code that came back. i cleard that code again a couple days ago and now no codes are coming up any longer. one other thing happening is that it is cranking longer before it will start. normally i would say 1-2 seconds to crank to start, now it will crank 3-5 seconds but not start, turn key off, crank again 2-4 seconds and it will start. i took it for an hour drive last night and had no issues, it started normally (normal crank time) and do not remember hearing rpm's fluxuate. after sitting for over an hour, i had to crank it twice to get it started, then could hear the rpm fluxuate and noticed for a few seconds that the idle rpm's dropped to around 500. i pushed the accelerator and the rpm's came back up to normal, but i could hear the rpm's fluxuate again. drove it home (hour drive) at highway speeds, 60-75 and had no issues. this morning had to crank twice to start it, but then it stalled out. primer was easy to push. i opened the bleeder screw and only fuel came out. tried priming again with bleeder closed, but could not primer would not get hard to pump. i got the truck to start, but it stalled out. sorry for the long post, but wanted to give as much info as i could. any thoughts/ideas as to what might be happening? 148k on the truck. thanks for any ideas anyone could provide. --Brian

[tammybrian2]

i opened the bleeder screw and more air came out. i tried to prime several times, each time i opened bleeder i got air. primer will not get any harder to prime. maybe another leak in the fuel line somewhere? will try pressurizing the tank today.

[rapidoxidationman]

If you've already found a return line to have a hole in it (weeping fuel?) my first guess would be a supply line with the same problem. Won't be easy to find because that line is under a relative vacuum so would be drawing air into the fuel system rather than visibly leaking fuel. Pressurizing the fuel tank (only a few PSI) might show where the leak is, but I'd also start saving some $$$ to install a lift pump.

[Kennedy]

In the long game what you really need is a lift pump. This will push the fuel to the filter and keep it full of fuel and not air. A lift pump will not fix your leak(s) but it will help you find them. It is often the filter head. A simple oring rebuild kit is all you should need for this part. Then check again for leaks.

The rolling/surging idle could be caused by aerated fuel.

Also it is my suggestion that you not use the plastic (Wix-Napa-Car Quest) fuel filters, only a good metal one. The plastic ones have been at the root of many calls of distress cured by simply replacing with a higher quality unit.

[tammybrian2]

i pulled the hose off the inlet to the fuel filter and pressurized the tank, seems it took about a minute or so for a very small stream of fuel to come out. put the hose back on and found another leak, this one coming from the supply line at the front of the tank, dripping from the quick connect.

[Kennedy]

When we install our lift pump kits we start at the tank sender (plastic) and replace the first section of hose completely. Not sure why yours would be leaking as they seldom do, but good to replace it and get the system under pressure.

http://www.kennedydiesel.com/docs/BasicLiftPumpInstallation.pdf

[tammybrian2]

well i bit the bullett yesterday and ordered a new set of fuel lines from the dealer. my fuel lines seem to be rusted at each point where they snap in to the plastic clips. seems to worse back by the fuel cooler. $483 plus tax from the dealer. it sounds like its a complete set, supply, return, cooler line, lines from tank and the two short tubes that screw in to the cooler. i'm going to tackle this job myself. anyone done this job before and anything i should look out for? anyone recommend a coating for these lines to stop/slow the rust? was going to order from linestogo.com, but found some links with google that made me think twice about ordering from them.

[tammybrian2]

and planning to install a lift pump in the near future.

[tammybrian2]

quick update, i ended up returning the $500 set of fuel lines back to the dealer, since their 'kit' did not include the two lines on the tank or the two short lines that screw in to the fuel cooler. Dealer wanted about $300 for the two lines on the tank. they were also steel lines.
i ended up finding a set of stainless lines on Rockauto.com. Supply/return/lines to cooler $336, the two tank lines (braided stainless), $91 and the two short lines that screw in to the cooler ($38). these two short lines that screw in to the cooler did not fit my cooler so i will be sending those back. called the dealer to purchase those short cooler lines.......they do not sell them. the only way to get those two lines.....was to purchase the cooler. so bit the bullet on that and purchased the cooler for $233.
as for the install, went very smooth. the supply/return lines came taped together in a couple spots....tried to put them in at the same time (taped together), didnt work so well. separated and put one line in at a time (also took the oil filter off, and maybe lost a half quart of oil) it was a little tricky at first, but actually went in fairly easy. maybe took 15 mintues to get that first line in.
the most difficult part was the fuel tank. not so much difficult, just a bit awkward getting the fuel filler tube up around the frame, and disconnecting the electrical connector from the top of the tank.
after getting the lines in, pressurized the tank. seems like it took 10-15 minutes to get fuel coming out of the hose going in to the fuel filter. primed the filter, cycled the ignition a couple of times, primed the filter and truck took a few extra seconds, maybe 5-7, and it fired up and ran. got a little bit of rpm fluxuation for a few seconds, but that went away and has been running ok since. so $517 for stainless lines, $233 for the cooler.

[Kennedy]

And still no lift pump which would have saved all the hassle and headache by placing the lines under pressure as they should be.

[tammybrian2]

i will be ordering lift pump soon from you!