tswcoaltrain

I am having problems with my lift pump on my second generation. I am running the holley blue off of the factory lift pump wire. The pump would lose pressure on and off about a week ago so I bought a new one and installed it only to find out I am having the same problem. I noticed too that when I bump the ignition to get the pump to run without starting the truck that the pump does not run for the 30 seconds like it did at one time. After starting the truck it runs basically no pressure untill the truck reaches the 20 MPH then the pump starts building pressure. I am starting to think the problem is in the voltage coming from the ECU. Can someone explain to me how this arrangement works. Also if the problem is the ECU can I just install a relay from the ignition to turn the pump on and just bypass the ECU pump circuit all together? Starting to scare me and I NEED this truck for work tomorrow!!!!

Meat Man

Ever find a solution? I'm searching for the same information!

Mine quit running for 2 seconds when Key ON.

It does not run when starter bumped.

I have an relay installed, triggered off the OEM wiring. I verified there is no voltage on the wire from the ECM.

Works just fine after starting engine.

Only problem I have heard of with installing a Key ON relay is that the VP44 doesn't like full pressure when starting.

tswcoaltrain

I installed a relay off of the main ecu wire to the Pump thinking it would cure the problem but it did not. Come to find out The problem was a bad ground wire.

Meat Man

which ground wire was it?

tswcoaltrain

The Holley blue pump is mounted on the side of the frame near the fuel tank. I had grounded the pump to frame with one of the bolts that holds the pump on the frame. I ended up running a dedicated ground wire from the battery straight to the lift pump and have not had any more problems since. Proof that a chassis ground is not the best form of a circuit. Hope this helps