newtododge

Ok, so I had a dead VP44.Funny thing is I had my pressure guage on order for two weeks before it died to monitor the LP. Turns out since we swapped the VP and got everything running today that the LP is fine. 14psi idle, 8psi while under full throttle. The problem is that when you first turn the key to the on position, the LP pumps up to fourteen. Once it reaches pressure and you hear it stop running(say in the case of waiting for the heater to heat up for cold start) the pressure drops but the pump never kicks back on. If I want it to get the pressure up again I have to bump it or turn the key off and then back on again. Is this normal? If not where do I start?

Also, just for reference, this is an aftermarket "high performance" lift pump.

The ruck is a monster with the new VP. I now know(from it;s incosistent behavior) that this thing was dying when I bought the truck last July. I'm in love with my truck again!

DuaneWKKC

Don't know if its normal or not, but mine does the same thing.
Turn on Ignition, pump runs for a sec or two, PSI up to about 10-12 psi(MAX) , soon as pump stops, PSI starts falling, If wait to start on, then PSI hits ZERO before off 90% of time. Dont think it ever did this befor my guage install... LOL (or maybe I just didnt know it )

DuaneW.

AlpineRAM

Perfectly normal- the LP is intended to run only with the engine running, and to prime the IP- meaning the ECM is doing the LP short cycle when you turn on the key and then will let the LP run with approx 50% duty cycle while cranking. The ECM will also let the LP run for approx. 30 seconds after a starter event (bumping the starter) regardless of whether the engine is running.
The VP44 can have troubles at extremely low rpm (like while cranking) if the pressure from the LP is too high.

HTH

AlpineRAM