Engine/Transmission (1998.5 - 2002) VP44 Overflow Valve - is mine ok?

[DDaubenspeck]

I've got a 2001 2500 2wd auto non-HO truck.



When turned off or in key-on but not running, it seems to loose fuel prime VERY fast. I'm getting a puff of white smoke at start-up.



I wonder if my overflow valve/check valve on the VP44 is working correctly. Attached are pictures of it and the shop manual diagnosis page.



In the picture, the small hole called out via red arrow ALWAYS leaks when tested. It leaks air (and therefore fuel) at any pressure.



The large holes only leak above 15 psi, which agrees with what the shop manual calls out is OK. The shop manual says the valve SHOULD open around 15 psi, and SHOULD NOT open at 10.



Is the small hole a constant bypass to cool the VP44? The shop manual does not specifically mention this!



Does everyone else's Overflow valve work the same way? Or, is mine defective?



I am using the BD fuel low pressure switch and LED, and not a real gauge. I'm using the Airtex walbro-style pump, which shows good pressure when my test gauge is installed - I couldn't pull it below 12 psi when loaded on-the-road.

 

[ThrottleJockey]

Change the thing out and see. How much is that bolt at Cummins? Can't be much, yeah?



Did you clean it out? is the check ball in there pitted? Is it cracked? C'mon, man! Fess up!



Seriously, try putting a new one in there. The VP-44 can be sort of... ... .



... . fragile.

 

[Bob4x4]

I have yet to get one that was failed... ... ... ... ... but anything is possible.

Loosing prime on a 24v is a time consuming task to repair. Buy some clear tubing ,systematicly ck each section of the fuel system

 

[bmoeller]

Change the thing out and see. How much is that bolt at Cummins? Can't be much, yeah?

They cost more than you think, at Cummins.

 

[ALepley]

They cost more than you think, at Cummins.

You aint kidding. When I took my vp44 in for the core I didnt take the bango bolt in with, they charged my 29. 00 because of that. #@$%!

 

[KrisKringle]

Cost of valve

They cost more than you think, at Cummins.

I just ordered one using the Bosch number; 1467445003. It cost less than 20€, and will be here tomorrow Hopefully it will fix the problems I have been having with pressure...

 

[dkoldno7]

losing prime

Hello, I,ve had this before and it turned out to be to o ring on the return fuel line on the back of the head. Hopes this helps,



D. K.

 

[KrisKringle]

O-ring???

Hello, I,ve had this before and it turned out to be to o ring on the return fuel line on the back of the head. Hopes this helps,



D. K.

Thanks, I will check it out. I do not see any diesel running down the back, buit I will take a look.



Here is the other thread on the problem: Erratic Fuel Pressure.



I am wondering how an O-ring at the other end of the system can have an impact on erratic fuel pressure... also I am not looking forward to trying to get to it... at the back of the block???

 

[Joe Mc]

Kris,

If you are experiencing loss of prime I'll share with you what ended up being my problem and fix.

The steel supply line that leaves the unit on top of the tank rusted and had a pin hole. It would start fine within 5 - 10 mins of a shutdown, but after an overnight sit it had to be cranked several times almost like it had run out of fuel. The fix a vulcan draw straw. A bit of a PIA to install as the tank had to be dropped (or if you are up for a bit more difficulty the bed can be removed) to access the fuel module but it has worked fine going on 7 years now. Good luck.

 

[KrisKringle]

Thanks, but...

Kris,



If you are experiencing loss of prime I'll share with you what ended up being my problem and fix.



The steel supply line that leaves the unit on top of the tank rusted and had a pin hole. It would start fine within 5 - 10 mins of a shutdown, but after an overnight sit it had to be cranked several times almost like it had run out of fuel. The fix a vulcan draw straw. A bit of a PIA to install as the tank had to be dropped (or if you are up for a bit more difficulty the bed can be removed) to access the fuel module but it has worked fine going on 7 years now. Good luck.

Thanks for the info. The draw-straw is already in... I have to write up how I did it, since the way it was done is different from the other methods...



The problem is not particularly lack of prime, as the truck starts fine. The problem is pressure. Here is the thread: Erratic Fuel Pressure



However, after replacing everything, checking for screens that were blocked, bucket tests, etc, I am inclined to believe the pump (FASS DDRP) is junk...



Thanks again... Jonathan

 

[Joe Mc]

Jon now that you said it "the pump (FASS DDRP) is junk...

I can't agree based on my own experiences I can only share what I've experienced with my Walbro unit. I got a big line kit, remote spin on filter kit and the 392 Walbro as it was sold by Glacier Diesel Products some years back. Unfortunately, GDP no longer offers the Walbo unit and now only has FASS products . . .

Anyway, I dialed in my psi to 22 via stacking little washers (supplied with the kit) inside the regulating valve that came with the kit and have never seen below 20 psi even with the Edge on 5/5 and at WOT.

So if you are looking to acquire an other than FASS system you may be inclined to do an internet search on Walbro and see what comes up.

I can't remember exactly when I went from the stock LP relocated to the frame but if I had to guess I'd say between 5 - 6 years back if not more and that equates to roughly 65-70k miles ago.