I talked to a good mechanic at the local dodge dealer. I told him I did not like the intank pmp pulling down to 3psi. I said it should be atleast 5psi. He said, not so. As long as there is pressure and not 0-1, then more fuel is being sent then is being used. Therefore you are circulating fuel. Kinda made sense. everybody talks about being above 10psi or so. Well, it seems unused fuel will eventually carry the temperature of fuel in tank and to say 7 psi is removing alot more heat then 3 psi in that application does not make alot of sense. What say ye

 

As long as there is fuel flowing thru the return line, more fuel is being supplied than is being used. But more excess fuel will return at higher pressures. Apparently this extra circulation from the higher pressure is needed to keep the VP adequately cooled and lubed.

The Cummins B factory service manual states that there should be at least 10psi at the VP inlet

 

[QUOTE
The Cummins B factory service manual states that there should be at least 10psi at the VP inlet[/QUOTE]

This is what cummins and chrysler recommend now.


http://dodgeram.info/tsb/2003/14-002-03.htm

 

No thanks. I've ran 22 pounds for the last 5 years and 100,000 miles on a 500+ hp truck and all on the same VP44. I don't trust their numbers at all. I'm also running a 5/8s drawstraw in the tank and see no pressure loss at full throttle.

 

The interesting thing is no one I know that has the warranty intank upgrade will even idle at 10psi hardly. Mine like most idles at 8psi and under load is 4-5 psi. They say its volume not psi and what I have is adequit. I am actually putting on a fass ddrp this week. Just dont understand everybody paying 500 plus for units that are WAY over done and are more for rockets then diesels.

 

One thing you have to keep in mind is that Cummins and dodge (now Fiat?) are/were in the business of selling parts. Even though they say 3 psi is ok, I like to see it a little higher, plus it helps me sleep better at night. On my truck its 10.5 psi @ WOT and 15.5 idling... since I put the FASS HPFP on, its a pretty boring gauge to watch....

 

but to get volume you must have pressure.. assuming you keep the same size lines.

-dkenny

 

i personally don't worry about the pressure unless its 0 mine runs 15 at idle and i see as low as 8 pulling my gooseneck and loaded to a gcwr of 30,000 at wot.

 

Mine usually had 6 to 8 psi at idle and just barely over 3 while pulling and totally stock. After installing the Vulcan relocator line kit and a new stock lift pump, I never see less than 12 psi. Those banjo bolts are VP44 killers!

 

I don't mind the lower pressures. I have replaced 3 VP44s in the shop this week. So, it keeps me fed! One truck with a weak relocated Carter. The other with a perfectly functioning in tank pump.

I don't recommend less than 8PSI ever. And I would prefer no less than 10PSI.

Dave

 

Do you sell high performance pumps? I read of VPs failing on HP pumps also.

 

As an idea either replace the bajo's that allow more fuel flow or drill them out as I did so they flow more. Obviously, don't drill them out too much so you loose the integrity of the bolt....as in this case, a little can go a long way.

 

We do. But honestly, there's a huge reliability issue there. So they are not for everyone.

Since a SO VP can go well over 600HP, most guys only look at them if they are tapped out on power.

Dave

 

i was told by cummins that it should not be less the 8 at WOT and 10 at idle. stock truck, anything less is an indication of weak or failing lp. never had to replace a vp on any of my trucks

 

As stated, the VP44 will fail with higher pressures. Less than great design.
But they will fail quicker, IMO, with borderline low fuel pressure.
I believe the 02 set up is superior to earlier designs and their VP44s tend to last longer. But no matter what you do, you will be replacing it.
Low end seems to be around 80,000 miles. Upper end is about 150,000 miles...so far, with some going far longer.

RJ