Engine/Transmission (1998.5 - 2002) When is lift pump supposed to run?

[BILLYGEE]

Question: When is the lift pump supposed to run, with key on, with engine running, everytime you bump the starter? I may have a bad harness and need to know this so I can fix my problem... (Truck doesn't want to start after sitting several hours and I have to bump the starter several times to get fuel up to the vp-44, I checked for leaks and don't believe I have any. )

 

[nps]

Runs for 3 seconds when the key is first turned to the ON (or RUN) position (not ACCY).



Runs for 25 seconds when the starter is bumped and the key returned to the ON position. Just hit the starter but let off before it catches.



You should be able to hear the pump running with the engine off. If you don't your pump may be out.

 

[hemijustin]

mine comes on when i turn the key on the for a few seconds. and then every time i bump the starter.



JUSTIN

 

[ToolManTimTaylor]

What's your FP guage telling you? Warm hard starts usually point to a VP but let's not jump to conclusions here.

 

[hemijustin]

What's your FP guage telling you? Warm hard starts usually point to a VP but let's not jump to conclusions here.

uh oh iv been having hard starts since i put my fass on at the begining of the week

 

[ToolManTimTaylor]

That can be something different. Too much head pressure (above 20 when starting) can do that too. How is that fass wired? On a relay and tied into the factory lift pump harness?

 

[BILLYGEE]

Must be the extension harness.

Thanks for the help guys. It must be the extension wiring harness I got from Vulcan. My pump doesn't run everytime I bump the starter. Believe me I don't have any trouble hearing it down where it is next to the tank when it runs. Sometimes I have to bump the starter several times to get it to run and have 16psi when it does run, obviously zilch when it isn't running.

 

[hemijustin]

That can be something different. Too much head pressure (above 20 when starting) can do that too. How is that fass wired? On a relay and tied into the factory lift pump harness?

the fass plugs into the factory lp wire but it also has a power and ground wire that hook to the battery... my fp is only 15...

 

[ToolManTimTaylor]

Yep Justin is right (Mine is that way) However some have been wired in the past with just a relay with the signal coming from just a key on position. That starts pumping the seccond the key is turned VS a timed pulse signal from the LP wire.