Air in fuel line

[86k10]

I have a 1008 that seems to have a problem with getting air in the system especially after sitting at night but will also bother if it idles long enough. I cannot find anything wrong with the hoses or the line on the intake side of the fuel pump. I guess i'll try either filling it up with fuel to see if it's in the tank or just run a line to a 5 gallon can and try that way. Anyone have this happen to you?

 

[gasser]

Check every hose line in the engine compartment ... see if there is any trace of fuel residue and drops. Have you changed the fuel pressure switch? - it's under the fuel filter. Or know that it has been changed? There was a WO back in the early 90's to have them all swapped out. I suggest changing that - that has bitten me on two CUCVs as well as both of others.

There is also a check valve in the fuel pump to stop fuel from draining back to the tank. That may have failed as well.
One last thing - you can apply 2 pounds of air pressure going back to the injectors from the IP, and see if you see anything.

Does it start ... run for a second, die ... only to get it started about 30 seconds later of cranking?

 

[Recovry4x4]

If you're drawing air, it wil probably between the tank and lift pump. I would check the lines very closely for a chave with an ever so slight of a pinhole. When the hole is big enough to be obvious, the truck will barely run if at all.

 

[Hasdrubal]

Might be a faulty fuel cap. Get it running, when you shut it off open cap to release pressure or vacuum,put it back on. In he morning if it fires, theres your problem. Drill a tiny hole thru cap or replace it. I had this happen on my M1009 took weeks of checking everything before I figured it out. All the "experts" recommended changing all the rubber lines, rebuilding IP etc...a costly guessing game.

 

[86k10]

Yeh i'm going to run it out of a 5 gallon can and see what it does, if it helps i'll start checking everything from the fuel pump back to the tank.

 

[86k10]

Well after finally taking the time to investigate, first took off the fuel tank to check the lines above and inside, nothing there. Of course only one thing left to check, the line running behind the cab to the tank. Logic says what can go wrong with a metal line right? Wrong! at some point in time, something had fell down behind the cab and rubbed a hole in it. At least problem solved.