ongoing fuel problem

[DThibault]

91. 5 truck has been giving me starting problems. Quite weird symptoms. If the truck gets under one half tank of fuel, it takes a while to fire off when cranking. Full tank seems normal. If I park it on a steep hill, (nose up) the symptoms worsen considerably. Then engine will crank till the primary pump gets fuel to the injection pump and off we go running perfect after some skipping and smoke. I see no external leaks on the injection pump but its like there is an air leak that makes it loose its prime. Pump has 180,000 miles but runs great after it starts. ANy similar situations that someone else has figured out? Thanks for any help.

 

[ptmoore]

sounds like a weak fuel pump,maybe an internal checkvalve is leaking. i would open the pressure side of the pump and crank the engine over and there should be fuel pressure immediatly. if no pressure or weak pressure i would suspect the pump or possibly a restricted intake filter in the tank. it sounds more like the fuel pump is leaking back its prime.

 

[cerberusiam]

Cracked fueline between LP and tank, crack or rust on the pickup tube inside the tank, or LP starting to go south.



Just one ofthe many things that can go wrong on a 15 year old vehicle.

 

[WJune]

Ditto what Cerberusiam said, if you are in the rust belt you are overdue for new fuel lines an hoses from lift pump to tank. If you want to test first, then mount a spare tank in bed with good tight lines to fuel pump an see if it makes a difference. Did for me.

 

[JLEONARD]

I have an 89 junker truck here in Ct... if you want to set it up out side then swap tanks we can work something out.

PM me

Jay

 

[DThibault]

I think we could be on to something. This winter I had the fuel pickup in the tank break off and just float around. I took one from a junk gasser and fixed it and the big problem went away( running out of fuel with full tank) I thought everyting was OK But now maybe it is the fuel lines. My 93 has plastic ones but from looking under the 91, they look to be metal. Thanks for the offer Jay, if I can't see something that stares me in the face I will PM you and take you up on it. Making maple syrup now and am busy as heck. Kind of praying for warm weather to put an end to it. I am also ready for green grass. Dave

 

[Moab4x4]

Me too

I started to have the same problem in the morning with too long cranks in the morning if I sit for more than 2 days. I have plastic lines and had the sender/pickup tube out this last summer and all looked good there. I think my problem is that I had it ALL apart this summer and probably have something loose or a bad oring or ???.

When I had this problem with old metal lines I used to hook an electric fuel pump up at the tank and pressurize the system and look for wet spots. I can't see this hurting anything, but how much pressure will the LP take on the inlet side without having any problems? I know on the old gassers if you had a failed diaphram in the fuel pump you could get gas in the crankcase.



Any thoughts on this or a spot that usually goes first? Ah the joys of old trucks. at least we can work on them. !!!!



Thanks for sharing your experience with us 'new' guys.

Ken