how to diagnose a fuel pressure regulator
 

how will i know if my fuel pressure regulator is bad?

not 100% sure but im sure somone will chime in but i would check your fuel pressure and if its low then it may be going bad.

Yea cuz right now I have to prime the car twice before starting it or else it'll like stumble/choke when it starts up and it sounds bad lol

Get a fuel psi gauge and hook it to your schrader valve. Then have a friend turn on the key and check psi. Then start it and watch the psi. If you unplug the vaccum line on the FPR with the engine running it will show the max fuel psi (WOT). I don't remember the exact #'s but I believe it should be between 42-47 psi at idle +/- some. Anything else would create a problem, you may have to rig the gauge to be seen from the driver seat and drive around to watch the psi when your problem occurs. Don't forget it could also be a clogged filter or bad pump, whatever it is your headed in the right direction.

i did replace the fuel filter about a month ago, and im thinking its the fpr cuz when i prime it twice before starting it, its fine. so how will i be able to tell if its the regulator or pump?

i believe the regulator is part of the pump on the f bodies and there is a pulse dampner on the fuel rail

Check your psi first if it flutters or is a random thing it's gonna be the regulator. Pumps are usually fairly simple because they for the most part will either work or not. A pump will not usually randomly quit, it will act up a few time then simply stop working. In your case your symptoms are likley the FPR. My truck (2000 GMC 1500) had a bad regulator, it would start, idle for a few seconds then stumble and die about the time I was putting it into gear. I played this game 2-3 times every startup for about a week, new FPR and problem fixed!

The FPR is on the back of the intake monuted between the fuel rails. It has a small palstic vaccum line comming off the top which connects to the passenger side of the intake.

http://shbox.com/1/fp_reg.jpg

Well the thing is is that once its running its fine, its just starting it up that gives me a problem

i was thinking ls1 lol:bang:

If its a problem only at startup would it be something other than a fuel pressure problem?

not so true. i had this same problem... it would try to turn over then it would start after i primed it.... i bought a 60 dollar FPR installed it less then 10-15 minutes and it solved my problem! no start up problem since!!!

Btw you can tell if its bad.... leave the car running and pull the tube off the FPR if it shoots out fuel at idle its bad... but if it drips out the its fine.

I am surprised it took 12 posts for someone to chime in with suggesting to remove the vacuum line and look for fuel. There should be ZERO fuel coming out of the regulator vacuum side. If gas comes out, the regulator is bad.

BINGO!

no gas should come out of the vacumn line....check it

didn't read the other replies but here's my check list for FPR

remove vacuum line and check for fuel smell or fuel itself
next have engine running with fuel pressure gauge hooked up, fuel pressure should be around 40~psi at idle and 43~psi at WOT, with the vacuum line removed from the fpr it should simulate WOT fuel pressure (43~psi) if fuel pressure is constant with or with vacuum line hooked up you have a problem

shit sorry i got it mixed up... NO FUEL COMING OUTTA THE FPR.

SORRY

cool guys ill check it out later today and hopefully the fpr is bad and thats the reason for my startup problem lol

put on the pressure gauge and its reading around 50 psi when running...bad fpr?

if its your FPR, when you change it make sure you clean out your fuel rails too. when mine went out it was because of a lot of dirt getting to it and the fuel rail where really bad

Well is 50 psi a bad fpr? I'm assuming it is, would this also be the reason my car is idling higher than I have it tuned to?