What is the fuel pressure with the vaccume line unhooked from the fuel pressure regulator? I tried googleing it and I find everything from 39 up to 45, and then some saying anything between 40 and 47 is within factory specs. wtf? Are the gm FPR's really that bad from the factory? I know on my 93 jeep 4.0, the factory fuel pressure with the vaccume line unhooked is 39 psi, no range, just 39 psi, its either right or wrong. Vac line attached can vary based on engine vaccume though.

My edelbrock fuel rails that go with my intake, uses a bolt on FPR. From what I can find online, it appears the edlebrock one is set to 45 psi, witch is a bit more than I want. (I do not have one, the intake and rails did not come with it) I started trying to figure out a way to attach a hose barb to the fuel rail where the edelrock one went, but as thin as it is (cause the hole is big) it was looking like I might be stuck with theirs, or buy another left side rail so I would have threads on both ends I could attach lines to, and use a universial adjustable one. I measured the hole and looked at the pull a part seeing if I could find any factory fpr that might fit. I stumbled across a lt1 intake setting in a beat up and stripped out buick, I looked and low and behold, the fpr on it looked almost identical to the pictures of the edelbrock one I saw online, just the fuel return line is diffrent. I remove it and measure, and its the correct diamiter. I buy it for a few bucks and test fit it when I got home. TA DA, it fits perfectly. Looks like they are using a lt1 style fpr. But what pressure is this thing gonna run at? I dont plan on running the vaccume line to it. I would really like a adjustable one, but those are so dang expensive!
According to my calculations, with the injectors I plan on using, somewhere between 39 and 41 psi seems like it would be ideal.