tiburon

Does anyone know if my 87 GT has an adjustable fuel pressure regulator? Either way, how do you check the fuel pressure and what should it be at (I'm stock).
Also, could arough idle be caused by by improper pressure? Am I correct in saying that the pressure is only made by the fuel pump and the regulator only controlls how much pressure goes by?

slickshift

No
With FP gauge hooked up to the schrader valve (bike tire valve looking thing) on your fuel rail
38 lbs or around there
Yes
Sort of...that's probably a good way to look at it (the reg doesn't make pressure, but keeps it AT something...the rest over that number bypasses and goes back into the fuel tank)

tiburon

how could the FPR cause a rough idle? Would this just mean that the fuel pump is bad?It has a slight hum to it...

samseed101

The diaphragm of the FPR could be ruptured and that's one way it could cause a rough idle. An easy way to tell... remove the vacuum line from the vacuum source but leave it attached to the regulator. Then aim in into a jar or something just in case it is bad. After it's pointed in a safe direction, turn the key forward to give the pump some power. You can even fire teh car up if you want (expect it to run crappy though.) If fuel sprays through the vacuum line, then you know the regulator is bad.

You can also check the vacuum line for any fuel or see if you smell fuel in the vacuum line to teh regulator. This, of course, is done with the car turned off

WhiteWindsor

If your having a rough idle, i would replace the fuel filter first if you havn't done it recently. The fuel filter alway's get's overlooked.