how to diagnose a fuel pressure regulator
#4
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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.
#5
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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?
#7
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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!
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#8
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http://shbox.com/1/fp_reg.jpg
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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.
#14
no gas should come out of the vacumn line....check it
#15
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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
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