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