Hey guys I hope you can answer a simple (hopefully) question.

 

Lately I've noticed my pressures dropping on my DDRP.  I did some research and didn't realize there is the infamous ball and spring pressure relief in that model as well.  So I stretched the spring out a 1/4 inch like most recommend and now my pressures are pretty high.  At idle I'm around 24 psi and 17 at WOT.  Is 24 psi too high for idle or is it OK?  The ball looked to be in great shape unlike some of the deformed pics I've seen.

 

Thanks in advance.

D

I think anything over 20 is not needed, and of course stay above 14. I believe the reason for wide range swing is restricted fuel lines. You can try to squeeze that spring all the way over night and see if it comes back to 20 or so.

I'd run it for a few days as it will more then likely drop a bit and see where it settles out. 

 

If it ends up back at the pressures you were seeing before either replace it with a 17psi Airdog spring from Vulcan, or tab in the top coil of the spring so the ball cant fall as far into the spring coil.

Edited July 23, 20177 yr by notlimah

Thanks guys appreciate the help.  I'll keep an eye on it as I always do.

 

I have another question that hopefully someone can answer.  I know the bypass valve in VP44 opens up at 14psi.  Does that extra fuel flow straight back to the tank or is it routed though the IP to aid in cooling.  I think  I know the answer but just curious

"

L8tr

D

On 7/22/2017 at 7:45 PM, SilverMoose said:

So I stretched the spring out a 1/4 inch like most recommend and now my pressures are pretty high.

 

I never suggest stretching the spring way too hard to hit the mark. 

 

I highly suggest replacing the spring and check ball. Then if you need adjusting the pressure then use washers for shims on the spring. 

1 hour ago, SilverMoose said:

Thanks guys appreciate the help.  I'll keep an eye on it as I always do.

 

I have another question that hopefully someone can answer.  I know the bypass valve in VP44 opens up at 14psi.  Does that extra fuel flow straight back to the tank or is it routed though the IP to aid in cooling.  I think  I know the answer but just curious

"

L8tr

D

The bypass valve is actually in the return line, so fuel is returned directly to the tank, but only after it has flowed through the VP to cool it

@SilverMoose it's routed through vp and continuesly flowing back to tank if pressure overcomes overflow spring that supposed to open at 14psi. And that's what cooling vp. 

Just to throw this out there it is my understanding that the valve opens to its max at 14 psi. The valve actually has a small bypass in it that always allows a little fuel by even at idle but as the pressure ramps up to 14 psi the valves opens fully. Someone please correct me if I am wrong.

Thanks guys, I figured that but wanted to confirm my assumption.

 

I will monitor my pressure and replace ball & spring if needed.

 

L8rt

D

Edited July 24, 20177 yr by SilverMoose

9 hours ago, dripley said:

Just to throw this out there it is my understanding that the valve opens to its max at 14 psi. The valve actually has a small bypass in it that always allows a little fuel by even at idle but as the pressure ramps up to 14 psi the valves opens fully. Someone please correct me if I am wrong.

 

It should have the by pass in it. Some I have seen do not.

 

24psi will not hurt the vp either. Old wives tale from pump rebuilders not wanting to honor warranty.

Just to update my pressure is still holding around 24/17 after a few weeks.  I do have one question though.  Does NAPA carry the copper banjo bolt washer or is this something I need to get from one of the online vendors?  

 

When I took the lift pump out I reused one of the OEM washers.  It looks like they have a little ruber seal on the inside of it.  I think that maybe it is leaking a little and randomly.  Every once in a while it takes a few extra cranks to start and there are no visible leaks.  I will probably replace the 2 on the lift pump and the 1 on the inlet side of the filter as they are the ones that came out when I adjusted the spring inisie the DDRP2

 

Thanks in advance

d

Dont know about NAPA but Vulcan and I believe DAP both carry the sealing washers. Buy some spares they are not expensive. 

Thanks @dripley gonna order me a bag of them from Vulcan

 

L8tr

D