fuel pump
Question.... Are you using a Liquid Filled Fuel Pressure Gauge?? If so swap it out to a NON Liquid filled gauge and see if that fixes your problem. I had the same issue until I got swapped to a non liquid gauge. If that is not it... then it is probably the regulator.
My Fuel pressure is Rock Solid at 6.5 PSI using the 4307M Regulator and the GSL-392 with a non liquid filled FP Gauge.
I suspended my GSL395 pump (15 psi version of the GSL392 which is 60 psi) about 1.5 years ago and I can't hear it running with the engine off! There are two self-stick rubber bumpers stuck on the chassis side, but I don't know that they've ever even made contact.
Note that the about to kink hose has been replaced with a 45° hose end and slightly shorter hose.
I used the stock 5/16" supply tube for the return and added a 3/8" supply. Am using a Holley By-Pass type regulator and its output pressure is inconsistent at best. Sometimes it's 7 psi, sometimes its 9 psi.
Question.... Are you using a Liquid Filled Fuel Pressure Gauge?? If so swap it out to a NON Liquid filled gauge and see if that fixes your problem. I had the same issue until I got swapped to a non liquid gauge. If that is not it... then it is probably the regulator.
My Fuel pressure is Rock Solid at 6.5 PSI using the 4307M Regulator and the GSL-392 with a non liquid filled FP Gauge.