Engine/Transmission (1998.5 - 2002) Lift Pump Signal?

[Shilohsho]

What controls the lift pump? Mine has started losing power during a 4-7 minute idle. If I turn the truck off and immediately restart if then it regains power. So, why is my lift pump quitting?

 

[JLandry]

The lift pump is powered directly by the ECM... no fuses or relays in between. I



If the lift pump is acting up, then either lift pump has an internal problem, or there's a problem with the wiring harness and/or connections, or the ECM has an internal problem.



Probably the first thing to do (cheapest) is to disconnect, clean, and reconnect the plugs at both the lift pump and the ECM (50 pin plug on the driver's side of the engine). Sometimes the contacts get dirty or oxidized and the lift pump losses power.



Next, you might test the power wire between the lift pump and the ECM for an intermittent short or open circuit.



If that doesn't help, then replace the lift pump. If that doesn't help and the original lift pump turned out to be good after all, keep it as an emergency spare!



You might want to read these threads:



https://www.turbodieselregister.com...-2002/200418-lift-pump-has-delayed-start.html



https://www.turbodieselregister.com...only/143678-intermittent-lift-pump-start.html



Good luck,



John L.