Can somebody tell me how rapidly should the fuel pressure decline to zero after a Cummins 24 valve running a 15 psi FASS is shut down? Should it hold pressure for a while or should it rapidly drop to zero? Another question is what fuel pressure would you expect to see when the ignition is turned on and the pump runs momentarily before the engine starts or the starter is "bumped"?

 

Not sure if this help but I'm using a frame-rail mounted holley blue lift pump and it drops to zero pretty much the second I shut down the engine. I've always thought that was normal.

 

mine drops fairly quick. my psi hits about 10-14. Bumping it the psi is 17. I have the holley hp150