Engine/Transmission (1998.5 - 2002) Lift Pump Acting up

[kdw75]

Ok, my last lift pump started acting funny in that when you would bump the starter and not start the truck instead of running you would here it run about 1/2 a second 3 or 4 times in a row. I replaced my lift pump and the new one worked fine for about a week then this one is doing the same thing. Both seem to run after the truck is started but they don't seem to be running unless the engine is. Does this make any sense? The way I can tell it is running is I can feel it vibrating when the truck is running. I have it mounted on the frame back by the tank and I have replaced all the wiring and connectors and it seems like the ECM or whatever just isn't giving it current. This is a new ECM after the dealer said my old one was bad so I don't know if that could be the problem or not. I also have surging problems and MAP sensor codes that aren't the fault of the sensor. I am wondering if all this could be related.

 

[rweis]

I would check electrical connectors first.



Bob Weis

 

[kdw75]

Well, I am not sure which ones to check. I have cleaned all the ground that I can find around the engine compartment and I have completely replaced all the wires and plugs on my lift pump up to the factory harness. I am starting to think my ECM plug is loose or making poor contact.

 

[kdw75]

Oddly enough I unhooked my batteries and replaced one of the positive connectors and after hooking things back up the lift pump is working like normal again.