This is on my brothers truck it's a 93 2wd dually. He just bought it, the motor has been replaced recently and it looks like the pump is also new. A couple weeks ago he brought it over and I turned his pump up, bottomed out the star wheel, set the pin deep, and removed the collar on the full power screw and turned it in a couple turns. When I removed the full power screw fuel spilled out of the pump, and then stopped. I put the screw back in and all was good, until today. My brother called me about halfway to Seattle and said that while he was cruising down the freeway with the cruise set the truck lost power and it felt like he had just pushed the clutch in. With the cruise off it still does the same thing, It idles and starts just fine but loses power randomly while driving. He says if he lets off the throttle and then gets back on it, it comes back to life for awhile then does it again. He finished his trip and by the time he got to his destination everything was fine again. My question is what could have caused this situation? Could I have gotten air in the pump when I had the screw out? and would that cause this sort of problem? Or does he need a new fuel filter? or a lift pump? Any Ideas would be appreciated. Sorry about the long post.

 

Sounds like mine behaved until I changed the fuel filter. When I got frisky on hills it might just cut out and then drop speed till the engine caught and ran normally. I changed a couple of fuel filters and it has never happened again. Some previous owners never change anything. A dead lift pump would do the same thing because to some degree the VE pump is self priming but of course can't handle high fuel demand. Change the filter and see what happens.

 

Check for intermittent contact on the fuel shutdown solenoid, also.

 

I second this! My truck did the same exact thing, giving it a little power twisted the motor just perfect so the shut down solenoid lost contact and cut the fuel... as soon as it did the motor holding the truck back pushed the motor the other way and so it would idle put a ring terminal on that thing!

EDIT: A new fuel filter on a recently purchased truck is ALWAYS a good idea, no clue when they last changed it.

 

Wiring connections on the VE can be a real problem. Replace the terminals, brush the pump connection until very bright, crimp the terminal a little to ensure a real firm fit and use some dielectric grease. Sooner or later this connection will give you grief. If a first gen doesn't fire up right away this is the first place I check. Only happens to me when I am trying to show how little it takes to fire up an old Cummins.

 

Thanks for all the help. The fuel filter is going to be replaced asap, I hadn't even thought about the wire on the solenoid being loose. How would I go about checking the lift pump?

 

The best way to check the lift pump is with a pressure guage. I check mine by manually operating the pump lever. It is a little tricky because the engine might have come to rest at the high point of the pump push rod. If you do not feel any resistance when you activate the lever it could be because the engine is in the wrong spot OR the pump could be dead. I put my truck in high gear with out the park brake and push it back a bit to get the cam positioned right. At some point the pump should develop serious resistance or it is weak. Sometimes when the lift pump is really bad it will leak fuel into the crankcase. If my oil level ever went up and there was no coolant in the oil, I would suspect a leaky lift pump.