2nd Gen Non-Engine/Transmission FASS DRP-02 and Fuel Pressure

[Leaky88]

99 Dodge Cummins, 5.9 Cummins, VP44, Stock, 2WD, 47RE

I have 2 questions concerning Fuel Pressure.

Item: 1
I’m finding my cab ISSPRO R5460R Mechanical gauge is off anywhere from 1.5 to 2.1 psi over what VpMax shows. Foregoing based on multiple reading taken at OEM Fuel Filter housing where gauge attaches and from the Schrader valve where fuel pressure tester is connected. Am I expecting too much accuracy from the ISSPRO?

Item: 2
Concerns FASS DRP-02 Fuel Pump Pressure.

I have a FASS DRP 02 fuel pump Mounted on the rail. I have it as an Emergency “back-up“ should my FASS 150 ever fail me on the road traveling.

DRP is 4 years old, and has seen very little use. I tested the Fuel Pressure with a VpMax Liquid Filled Diesel Tester and it’s only putting out 13-13.5 PSI with reading taken at OEM fuel filter housing. The pump is suppose to put out 16-18 psi, or at least that what it’s advertised to do. I have found very little information about the DRP 02.

Since warranty has expired, I removed the aluminum mounting plate to expose spring and ball. The spring is Yellow, .620 high, .285 wide.

Q. Are there replacement springs available to increase Fuel Pressure? Or do I find a generic spring substitute and trim for desired result.

I want the maximum FP but do not want to burn the motor out. I prefer never to go under 14 psi for Heath and longevity of VP44.

Thanks.

Leaky

 

[BigPapa]

Sounds like you need to contact FASS.

866-769-3747

 

[Ozymandias]

Springs are available but take a hell of a time googling, ask me how i know....

You want the spring for the 03-08 Version, that puts out that much pressure,16-18psi.

I changed my spring to a 12psi from another Modell.

 

[Hohn]

Don't feel a need to run more than 12 psi or so. Cranking up the pressure doesn't cause more fuel flow through the pump and it won't run any cooler.

 

[PMalin]

I'm no Fass expert but on my 2001.5, I installed one of the relocation kits and bought a Carter CRT-P4601HP if I recall correctly. I then later discovered I needed to install a check valve a little more toward the engine, so it wouldnt bleed down while sitting and allowed me to get easy starts as I should. So, been running this for some time, but my fuel pressure stays positive in all conditions but ranges between 5 to 8 psi (MaxTow Ga Installed) depending on how hard I get on it. 1 psi was lost installing the checkvalve. But since the VP44 bleeds back to the return line anything it can, over a certain pressure (certain amount of flow returning) My pump does not overcome that and give me a higher pressure reading. I am not too worried so long as I see a positive pressure reading, hopefully 5 psi or better. Forcing a massive flow into the vp44 (head pressure) more than it needs, I just dont see that as being necessary for a standard truck (Racers maybe another matter) Just my opinion at this point, but feel free to comment.

 

[petersonj]

So, been running this for some time, but my fuel pressure stays positive in all conditions but ranges between 5 to 8 psi (MaxTow Ga Installed) depending on how hard I get on it.

I am not too worried so long as I see a positive pressure reading, hopefully 5 psi or better.

In my opinion, you are one of the few that has some understanding of the lift pump's purpose. You are correct in that as long as there is a positive pressure at the VP44 injection pump inlet, then there is always a proper amount of return fuel flowing from the VP44 to the fuel tank. It is the VP44's internal fixed displacement vane pump that ensures this will happen, not the lift pump.

- John

 

[Gary - K7GLD]

YUP - my Walbro pusher provides a steady 15 psi to the VP44 under all driving conditions - but any significant psi above a few psi is all the VP44 is actually going to deliver to the engine - my "extra" psi is just for my own warm and fuzzy feeling... (or thinking?)

Actual upgrading in the lift pump area - in my case, is more about quality and reliability of hardware, than higher psi - and back in the day, the OEM pumps were failing quite frequently - even Dodge/Cummins were aware of that, and provided their own updated lift pump setups...