Engine/Transmission (1994 - 1998) Rebuilt P-pump won't push fuel

[DHixson]

Just got my pump back from Piers. I had it rebuilt and modded. Got it back on the truck and turned the key and now I cannot get fuel to the injector lines. I checked the supply line off of my FASS and it is flowing fine. I pulled the return line off the pump and got nothing coming out. I checked the starter solenoid lever and it hits both stops inside the pump. I watched the solenoid as the engine was cranked and it works like it is supposed to. I even unplugged it and worked the lever manually while cranking and still nothing. The truck just cranks and the injector lines are bone dry. I am officially stumped!

 

[JGK]

Loosen the banjo bolt on the top of the fuel filter and either pump the primer button on the lift pump a bunch or run your FASS until fuel leaks around the banjo bolt. Tighten it down and crank it. It should start right up in just a few cranks.



If you've bypassed the stock fuel filter and are supplying the P-pump directly from the FASS with separate filter, just make sure there's fuel coming out at pressure at the last fitting feeding the P-pump.



If no fuel shows up at the fitting or banjo bolt, you have a fuel supply issue prior to the P-pump.



-Jay

 

[EKlem]

How long have you let your fass run for? The P7100 holds a lot of fuel, you might not have filled it yet.

 

[DHixson]

How long have you let your fass run for? The P7100 holds a lot of fuel, you might not have filled it yet.

I let it run for several minutes and I never heard the fass motor change tone(changing tone meaning when it goes under full pressure and begins to return fuel to the tank) like it usually does. I am wondering if the P-pump may be airlocked or if I need to add more oil to the bottom of it but I am unsure and don't want to do anymore until I get some more info.

 

[LSchulz]

EKlem is right, that pump holds a lot of fuel, and it sounds like you haven't filled it back up yet. The DT466 on the bus has the P7100 as well, so I've had plenty of experience with airlocking it. Open the valve (10mm wrench if I recall), and run the FASS until you have good solid fuel coming out (get yourself a drip bucket, it'll fizzle out lots of air and fuel in the meantime). Open up the first two or three injector lines on the top of the pump and have someone crank it until you get fuel coming out (it might even start on a couple cylinders) . Tighten the lines back down, and away you go.

 

[DHixson]

sure enough it was airlocked. thanks for the advice fellas.