I have been working on this truck off and on as time allows and researching this site for ideas. The truck will start and then die, with foot to the floor.

I have chased good fuel all the way to the line going to the IP. I have not pulled the inlet line off at the pump yet cause i cant get in there, but i am getting ready to do that next.

Something interesting happened to me today that i thought i would throw out there, i pulled the top off the IP, which was full, pumped some fuel down so i could see the working parts inside. I put the top back on and decided to start it and it ran for a bit, like 15 seconds and then died.

I pulled the top off the IP again, pumped fuel down inside, put the top back on and started it up and again, it ran good for about 15-20 seconds, like it will run until the IP fills up and then it dies???

Ideas?

 

could be a clogged line, or the sock in the tank is bad.

sucking air from anywhere? how is the fuel filter housing?

 

It is a brand new filter, and I have good fuel from the lift pump right up to the outlet side of the filter that goes to the IP.

I cranked on it with the top off of the IP and it filled really slowly while cranking. How fast should the pump fill while cranking?

Not sure about air.

 

Sounds like your sucking air before the fuel pump. Have you tried switching tanks?

 

I talked over the issues i was having with a mechanic and he told me that IP pistons will not pump if the pressure inside the IP becomes to high, so the next place to investigate was the return line out the top of the pump.

I pulled the cover off, removed the return line hose, and pushed some air back through the fitting, put it back together and it fired right up.

So, it appears that the return line had gotten plugged, which speaks to why the engine would run until the IP filled up and built pressure against a plugged return line, and then would quit pumping, thus killing the engine.

 

yup makes sense