My oem lift pump was running low pressures (6-7) at highway speed. Engine ran perfect but started hard, sometimes impossile to start when hot. Got tired of having to leave engine running continuously on long trips, so I installed a Holley black lift pump back by the tank, running through the original pump. The pump is supposed to be factory preset for 15 psi, but my gauge was showing 25-30#. I drove it 150 mi. today and it started harder than ever (but performed perfectly as usual when running). After I got home, it sat an hour and took a long time to start. I drove 5 miles. An hour later, it wouldn't start.
Questions:
Why is my pressure so high?
Did the high pressure cream my VP44?
What kind of regulator to use-the one for the Holley Black is only adjustable 41/2 to 9#?
Thanks, Bud

 

Let's see. 15 psi at tank and another 7-9 psi from suction. Yea 25-30 sounds about right. Probablly more than a worn VP pump really wants.

 

doesn't sound right at all. Holley black is good for 14 P.S.I. max. cascading the discharge through another low pressure pump is not going to give you 30 P.S.I. At least not without a little magic.

 

1) The combines pressure output of pumps in series can be higher than you think. But other explanations like a return line restriction and such also need to be ruled out.
2) Not likely. VPs don't like higher pressure when trying to start--once the engine is running, high FP isn't a problem.
3) Use a BYPASS regulator with a return line-- I'm partial to aeromotive regulators.

 

didnt think the black put out enough volume thats why everyone says to use the holley blue.

 

What is the number for the Walbro regulator usually used with their gsl 391 pumps?
Thanks,
Bud

 

you got a good clean tank vent ???