It's been almost 2 years since I've seen the insides of a VP44 and my memory is starting to fade. I'm stumped.<br><br>What would cause the VP44 to loose it's prime after sitting off for 10 to 20 minutes or so? <br><br>Here's some information.<br><br>Happens about 80% of the time when truck is on level ground<br>Happens more with an empty tank<br>Happens almost all the time when the front of truck is parked up hill<br>Doesn't happen much when the front of the truck is parked down hill<br>When it does happen, the engine will start after letting lift pumps run for 15 to 20 seconds<br>No codes set<br>No visible fuel leaks<br>Fuel bypass valve is OK (Cummins wants over $100 for a new one, by the way)<br>Fuel pressure after filter - 22 lbs @ engine stopped 20 lbs @ idle 15 lbs @ WOT <br><br>Thanks

 

If you fuel pressure is to high you will get a hard start as well.

 

I know on mine, my fuel filter drain thingy leaks and if the truck sits for a while, it will lose it's prime.

 

Like Stakeman said. Your fuel pressure is to high. That is causing your problem. You need to get it down to OEM spec's.

 

Go here for a review of the VP44 operation, it also states the pressure output for the lift pump. http://www.dodgeram.org/tech/dsl/ISB/Vp44.htm

 

nice sight pitbull

 

[quote author=Pit Bull link=board=4;threadid=10490;start=0#100365 date=1044378906]<br>Like Stakeman said. Your fuel pressure is to high. That is causing your problem. You need to get it down to OEM spec's.<br>[/quote]<br><br>If you wire a relay and tap into the stock wiring harness (which I am hoping Bart did) then it solves that issue, it will cycle the lift pump, I noticed this back with the stock pump and a reflash, change the way the ECM ran the lift pump on startup.

 

I tapped into the electrics for the pusher pump using the pigtail extension avialable from Cummins and a relay, so that pressure is reduced during starting. It's not the starting pressure which seems to be the problem, I think. Cranking psi is 5-7 lbs. It acts just like after changing out a fuel filter and the VP44 has lost its prime.

I understand it could be the return lines which are letting air into the system thereby draining the fuel out of the VP44 back to the fuel tank. This is a notoriuos problem on the 12vs. Haven't had time to check this solution out yet.

I'll check the fuel filter drain. Thanks for that heads up.