Engine/Transmission (1998.5 - 2002) No power to F.A.S.S or stock LP

[GWarren]

Noticed this morning before heading to work that I didnt hear the F. A. S. S. working before I started the truck. After starting the truck the fuel pressure remained at 0psi at idle (definitely not working). Started troubleshooting it when I got home. I tested the all the wires that run into the fusebox(solenoid?) that came with the F. A. S. S. There is 3 red wires and 1 green running into the fusebox. 1 red wire constant voltage 12. 69v(connects to battery), the other 2 red wires remained at 0v with the ignition turned off, turned on, and the truck running. As a test I unhooked the F. A. S. S power connector and reconnected it to the stock LP connector (no power with key cycled and truck running). Checked the fuse in the engine compartment for the fuel relay and it looked good. Any ideas what to check next?

Thanks

Gary

 

[rkressg]

This might sound bad, but the Lift Pump is powered though the circuit logic of the ECM. Anotherwords, the ECM physically powers the Lift Pump, which inturn is used to power the relay on the FASS. If this circuit is open, than there is a chance that it is a problem with the ECM. You can bypass this by finding a power source that only works when the engine is running, and use this to power the FASS. If you do this, you need to ensure that this power source turns off while cranking, B/C excessive fuel pressure during cranking can cause a "hard start" condition.

-Rich