Engine/Transmission (1998.5 - 2002) Fuel Pressure Clarification

[rjrkihap]

I’ve been following the fuel pressure threads (as I too have recently lost my vp44 and lift pump) and am a bit confused. Cummins and Dodge (Bosch also) state that as long as your lift pump is putting out 5psi your vp44 is just fine. In fact, they will not warranty the pump until THEY can verify less than 5psi. However, I have also read that as soon as you drop under 10psi your vp44 is in danger of being damaged. I’ve also read that those who have had the in-tank lift pump retrofit are seeing pressures under 10 right after the install with Dodge commenting that flow is what’s important and not pressure.



My question is who’s right? If the under 10psi rule is correct, then a lot of us will end up replacing our lift pumps ourselves even if it’s still under warranty.



Thanks



Ron

 

[Thomas]

Actually Dodge (the company providing the warrantee) doesn't look at pressure on the 1998. 5-2002 transfer pumps: http://dodgeram. info/tsb/2003/14-002-03.htm

 

[cyborg]

Dodge must be run by FEMA

 

[Fishin Guide]

With regards to fuel pressure, more is better, to a point.



There is an overflow valve in the VP44 set for around 14 psi. I try to keep it open at all times to keep fuel flowing through the pump.



I have no expertise in this matter other than I feel it's the right thing for my truck.



Dave

 

[Jack in Alaska]

Ron,

You asked the exact question I have.



I had my lift pump replaced in Pendleton, Or. by a DC dealer trying to repair my hard start problem. They installed the new in-tank pump and it put out 10psi at idle and 8psi at WOT. Now after several weeks of use the pressure has increased to 12psi at idle.

It did not solve the hard start problem.

Several days later I had a new inj. pump installed in Salt Lake. They told me that the new inj. pump would not "live" with 10psi and that was directly from Bosch.



Where does that leave me. I am now my own warranty station and I want that inj. pump to last 157k miles like the last one. Oo.

 

[Steve Campbell]

"A long time ago, in a thread... . far, far away" ("Pumps, lines and whatnot") there was a lot of speculation on this and other matters. Personally, I feel that the internal pressure valve in the lift pump is what usually fails... and the reason it fails is that it is always opening and closing. I have my vehicle set up with a line coming out of the top of the fuel filter housing (pre filter) with a needle valve and a hose connected to a "t" in the return line. I keep the lift pump pressure dialed in at 10 pounds or less so as to not cycle the internal valve in the lift pump (hoping for longer life on the aftermarket Carter 4601HP than the factory lift pump that only lasted about 25,000... the current system has been in use for approximately 95,000 miles).



There is a longer story here, but this part seems pertinent to the discussion at hand.

 

[rjrkihap]

So if I am reading this correctly, then anything under 10psi (at any time be it idle or WOT) will start to kill the VP44?!?



Ron