I have been having a pretty good pulsation in my fuel line. I thought it was the holley blue pump I put on last year.
I bought a rebuild kit and got the @#$% pressure relief plunger backwards and put around 30PSI on the CP3 inlet. (That is where my FP gauge is connected with a tapped bajo bolt)
Had problems with low fuel pressure after that. 7-8 idle 0@WOT

Bought new blue pump. Now 10-11 idle and 2psi WOT

I also noticed that when i turn the key on the pump builds pressure and then quits. Before the pressure would hold, now the pressure drops quickly.


Is my cascade overflow valve stuck open ????

If it is, how difficult is it to take apart.

I grew up doing engine overhauls and I do all my own maintenance.

 

The COFV is past the CP3's supply pump. I would guess if you have a return pulse from it you have more problems than the valve.

It sounds more like you have a problem with your holley pump but it could be a problem with the CP3 also.