sucking air? help

[olwhitey]

a friend of mine jus got 95 cummins. the guy said the fuel pickup tube or somethin had a hole in it and would suck air. we dnt know if he knew what he was talkin bout so we jus said ok. we ran new fuel lines from the top of the tank to the pump. the old ones didnt look good and were ghetto rigged somewhat.

heres the prob. while driving down the road it will start to pulsate, shake the truck real bad. then it hold the throttle down by itself trying to get fuel i think. then it will jus die. and you have to crank on it for a min to get it fire back up but it will start doing the same thing within a 100 yards. does this sound like its sucking air somewhere in the system or the lift pump is going out?
any ideas are greatly appreciated.

 

[PRattenbury]

You might want to try bypassing the fuel heater. They're notorious for leaking.

 

[kawi600]

I ran hydraulic hose from the tank to the engine bay too. Those fittings on top of the sender are prone to rot out and allow air in as well.
Id wait till youre low on fuel if possible, then drop the fuel tank. You can get a vulcan draw straw that replaces the bung with the pickup lines in it, and get a small piece of hose and connect it to the stock pickup inside the fuel pickup assembly. The draw straw does indeed work on old 12v trucks. I wouldnt use the straw though since you lose the seal on the pickup .
another tip is that mcmaster carr sells these sight glass things you can use to put in-line and watch for air problems.

 

[wildmanben]

I am chasing a similar problem on a buddies truck. Has to crank for 30+ seconds before it will fire and then misfire and sort of run and finally it will smooth out. Got a FP gauge on it and as soon as you shut if off the fuel pressure starts dropping. Overflow valve checked out good. Going to swap lift pumps and see if that fixes it.