Engine/Transmission (1998.5 - 2002) Lift Pump starts after long wait

[Jerry J]

My lift pump used to prime right away when I turn the key to on, now it won't until after a long wait or after I turn the key on and off several times. I replaced the LP but no change. I have a raptor pump. I also have a new injector pump installed. Anyone have a solution?

 

[JLandry]

Jerry,

The first thing I'd do is verify the pump is getting power when you bump the ignition key (don't crank). Use a multimeter and start checking at the Raptor connector, then work your way all the way back to the 50-pin connector at the ECM (as needed). At the ECM connector, pins 15 and 35 supply power to the lift pump harness. They have 18 gauge yellow/white colored wires. Use the engine block or chassis as the ground.

If nothing is wrong with the wiring harness or ground connections, then it's an internal ECM hardware or software problem.

Best regards,

John L.

 

[FCrowder]

Is your wait to start light coming on as soon as you turn the key or does it stay off until the pump comes on? If it is delayed then its probably the ecm.
You can type in wait to start light and the are many threads about it. some people said they cleaned grounds and electrical connector and that helped but most had to replace the ecm. Francis

 

[Jerry J]

both replys really help. I think maybe it is in the ecm area because sometimes my wait to start light comes on and sometimes it doesn't. I'll search the forum on the wait to start. thanks

 

[KCramer]

Hi Jerry -

Mine is suffering (maybe) the same problem. If the truck if off awhile, the lift pump starts just fine for two seconds, shuts off, then comes right back on when cranking. If its only been off a bit (less than minutes), the pump doesn't start after the initial 2 second run. From the SM: "The transfer pump is self-priming: When the key is first turned on (without cranking engine), the pump will operate for approximately 2 seconds and then shut off. The pump will also operate for up to 25 seconds after the stater is engages, and then disengaged and the engine is not running. The pump shuts off immediately if the key is on the the engine stops running."

I have found that (in hot weather) if I turn the key to on, and engage the starter withing the 2 second window, the truck will fire just fine, and the lift pump will continue to operate. I'm not sure about cold weather, since mine only started doing this recently.

Searching the forums (fora?), there seems to be a problem with the ECM, and it's not properly re-starting the lift pump as it should. There are work arounds to provide power to the lift pump from the injection pump relay - I am planning on wiring this in for the winter, in case this continues. I am not sure how this situation will sit once the heaters come into play.

another thread: https://www.turbodieselregister.com/threads/235173-Lift-pump-will-not-run-when-key-is-turned-on

 

[arthur]

Relay

My lift pump used to prime right away when I turn the key to on, now it won't until after a long wait or after I turn the key on and off several times. I replaced the LP but no change. I have a raptor pump. I also have a new injector pump installed. Anyone have a solution?

This is my first time on turbo
I had a 2002 dodge 2500 same problem
I traced it back to a relay that is in the center of the windscreen under the hood there was two relays together
when you turn the key it puts power on the relay which then powers the pump
I changed the relay and no more problems
best regards art

 

[Jerry J]

my wait to start light never comes on now. If I wait about 10 to 15 seconds I will finally hear the pump and then it starts.