Engine/Transmission (1998.5 - 2002) lowest recommended PSI to VP44 at WOT?

[Devil Black Diesel]

What's the lowest acceptable/recommended fuel pressure at the VP at wide open throttle (short periods of time)? 5psi? 7psi? 10psi?



Thanks

 

[mhenon]

Here's what Blue Chip Diesel has to say:"We proved on a dynomometer in 1998 that if you have 5 PSI, under load, you can make all the power available from a VP44, and 5 psi will provide plenty of return fuel for pump lubrication. We do not recommend running more than 12-15 PSI as that does NOT help the fuel system in any way. In fact higher pressures could diminish fuel delivery to the rotor and make the truck run worse at high RPM and possibly overheat and damage the fuel bypass solenoid. "

My fuel system is setup not to go below 12psi @ WOT but that's just me.

Mike

 

[rweis]

I think the VP44 is calibrated @13. 5 psi regardless of the rpm (idle to wot).



Generally it is thought that +- 3psi is ok before the steel fuel diaphram starts to deflect beyond . 5mm (limit) and starts to dammage its seals.



Hanging around 12 - 14 psi at the VP44 inlet seems to work well.



I think Blue Chip Diesel is a VERY knowledgable dealer with a very long excellent track record and I can not substancially refute their findings, but I like to hang around 14 psi.



Bob Weis



A Walbro 392 can easily provide that pressure when properly bypassed.

 

[JR2]

I remember in the old "Pumps Lines and Whatnot" thread that someone put a flow meter on the return line and the return flow to the tank did not drop off until around 3 psi or so. I have always had my low pressure alarm set at 7 psi and have had no VP failures in 50K miles (running big sticks and Drag Comp).

So in short, no less than 5 psi is what I would say.

 

[mhenon]

Your 7psi low pressure light should keep you certainly out of trouble.

Mike

 

[Joe Mc]

I recall reading somewhere that anything less than 10 psi is a no no regardless of throttle position

 

[Jed]

I have had 19 lbs for 3 years and 100,000

wot 15 or 16 lbs

fass and replaced vp at the same time



I do not know if this is best or correct but it has worked longer than the stock stuff did (70,000 dead vp)



jed

 

[SGevers]

Sorry to dig this one up but I have noticed since I installed my BD low fuel pressure light it will light up at WOT only on the quadzilla 70hp tune. Is this normal??

 

[AllianceDiesel]

honestly if you are going anything over stock your gonna want a fuel pump, I have installed glacier diesels pump and it is awesome and cheap.