I there something I need to do to stabilize fuel pressure? Mine is significantly different almost every time I drive the car. I am currently running a Mallory FPR with return and a Mallory FP. I use the respeed pressure gauge. I had the same issue running a holley FPR dead headed with either a holley red or the mallory FP. I thought going with the return was going to solve the problem but it hasn't.

I can range anywhere between 1.5 and 4.5 when I start the car cold. I re-tune it around 2.5 after the car has warmed up, and next time I start the car cold it is off even if I let it warm up again.

Any suggestions?

 

Take the fpr apart, clean it and check for machining burs. I've had the same problem. After my 3rd fpr, I finally found a stable one.

 

which one did you end up with?