My fuel pressure is going crazy at WOT. If I disconnect my inline pump, what should the idle FP be? I'm trying to determine if my intank pump is dying, or if I just need a new FPR. The Oring isn't damaged. There are 175k miles on the intank and the FPR, so one of them is probably a goner.

 

either 56 or 58 I THINK.....when you say "crazy"....."crazy" how?

 

If you have the vacuum regulator hooked up, you should probably see low-mid 50s fuel pressure. When driving under mild throttle (no boost) it should get back to the 58psi pressure. Under boost it should go over 60.

 

For anyone wondering, it was the inline causing the erratic fuel pressure. I disconnected the relay on the inline, and the stock pump by itself will steadily hold pressure. The inline must have been worn out and was doing more harm than good. I'll still need a new inline though, because it slowly starts to drop after a few seconds.