fuel problems

[nape]

First lack of fuel slow sluggish. Changed fuel filter, almost never got it to prime up. Finally fushed the fuel up with air pressure. Truck cranked and ran great for about 200 miles the following day on a trip. After that it began to weaken and eventually quit. I got the truck running and over to a friends house. The truck sat for 9 hours, cranked fine ran great for about 200 miles on the way home and then started the same thing. I got it home let it sit went over to a friends with it running terrible. When a left there it would hardly move but began to run better in a mile or so and got to running pretty good. When I stopped at the stop sign, I smelled fuel and it was running fuel all over the ground. I could not find the leak so I drove it home. A week later when I could look at it, no leak. I removed the intake and let it run for about 30 minutes, no leak. I still will not run, seems to be starving for fuel. I replaced both flexible lines under the intake and am moving to the other flexible lines before the charge pump. I think I will also install an electric pump while I am at it. Any ideas? How can it leak and then stop? Nape

[DmaxMaverick]

What year is the truck? Does it have a mechanical lift pump?

If it has a mechanical pump, that will likely be your problem. When they fail, they will usually dump fuel out of the weep hole (ruptured diaphram). The leak will continue until all the fuel in the fuel lines is out and the level in the tank is low enough to not drain, or the prime is lost (siphon). Next, the injection pump will suck air through the leak. The end result is no leak and an engine that won't run.

Mechanical pumps are inexpensive and relatively easy to replace. Search for detailed instructions and tricks on how to replace it, if you need to.

[nape]

It's a 90 model with a mechanical pump. I have replaced all the rubber lines and this did not help. I forced air into the fuel line at the mechanical pump purging the lines all the way to the tank in case of restriction. This did not help. The mechanical pump primed up fine after this. I am wondering if it is the injector pump or maybe a partial failure of the kill switch? Nape

[jcomp]

Did you also replace the rubber lines under the truck, between the tank and the engine compartment?

[nape]

Yes I replaced the lines under the truck. I can not figure out where the diesel could have leaked from and how it could have stopped. I am down to replacing the kill switch or injector pump. Nape