I finally got around to hooking up a fuel pressure gauge. I tapped the banjo bolt and ran a line into a guage on the steering column. I put a ball valve, and then a needle valve right after it to keep the pulsations down, and the ball valve in case it starts leaking.
My question is i am seeing about 12 to 14 psi at idle, and about 2000 rpm it tops out at about 18 to maybe 20 psi. I have a holley blue on.
Is it because of the holley? should i get rid of it? is that enough pressure?

 

Why in the world would you be running a Holly fuel pump on a 12V Cummins?

You are a starving the injector pump.

Cummins' pressure specs are 17-22 psi at idle, 25-35 at 2500 rpm no load,
Pressure should never drop below 25 psi under load

 

ya thats what i was thinking, it was on it when i bought it and i just never thought to pull it til recently i got thinking and put the gauge on.
I will pull it asap.
thanks a bunch.

 

Does it still have the Lift Pump on the block?