Fuel Pump Running
 

Just finishing up my 5.3 LS conversion and have a fuel pump question.

Is the fuel pump suppose to run all the time while the key/engine is on. Or does turn on of off according to fuel pressures.

Re: Fuel Pump Running
 

when the key is first switched to on with the engine not running the pump should run a few seconds until pressure is built up....then it shuts off until the pressure drops again..(usually from cranking)....then it comes back on when the engine is running and the pump head pressure drops...if the engine is running the pump will most likely run constantly. ..

Re: Fuel Pump Running
 

The fuel pressure has nothing to do with whether or not the pump actually runs, it runs off RPM signal from the the crank or cam position sensors. As long as the PCM sees in RPM from those sensors it turns the pump on, if the RPM stops it shuts the pump off after a couple seconds. If yours is running constantly then you have some kind of problem, most likely not wired right.

Re: Fuel Pump Running
 

Ok thank you. That helps me with my troubleshooting.