Morning all! Newbie to the site! Recently got myself an 02 Cummins after selling my 06 so I'm new to the VP world. I'll give you a quick breakdown on the parts installed: AD 150 Lift Pump, upgraded VP (don't know what model/brand but its supposed to be high flow) and 100hp injectors. I had a problem with my truck not starting shortly after I got it. I traced the problem to the signal wire for the relay that operates the lift pump when the key is turned on. The voltage would spike and pull the relay in, then it would drop off almost immeadiately and the relay would drop out. This would not give the Air Dog any time to prime or run, therefore, dead truck! My question is this: Where does this signal wire originate(followed it to a large wiring harness ) and does anybody have wiring diagrams for it? Anybody had a similar problem? Thanks in advance for the help!

 

Well the relay is doing what the ECM is telling it to do.On the VP the lift pump curciut will only turn on for 3 seconds tops to prime the VP if it would turn the lift pump on and leave it on until the truck was started there would be alot of injection pump diaphams blown up. The wire goes to the ECM.

Are you having hard starts?

 

What else he didn't tell you there, was that your fuel pump relay is incorporated in the ecm, and will typically cycle for 2 seconds when you turn the key to on. you will know if it is working correctly if when you just bump the starter without cranking, the fuel pump will cycle for approximately 25 seconds

 

Thanks for the insight guys. I believe I'm now looking for a new ECM! I gather I can expect to spend a few $$$ hey?

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BTW, no hard starts. It was a NO start that led to the troubleshooting. If the wire that runs to the lift pump comes directly from the ECM, I definetely have a fried ECM. Sucks cause' I don't have any other issues now that I bypassed this wire and just temp wired it to an aux power source.

 

did bypassing your ecm for your fuel pump power supply get her running? if so, have you checked for a signal out of the same wire where it comes out of your ecm? I mean before you go spend big $$ on a new ecm.