Fuel Pressure Test Values For Review....

[mike g 09]

OK. I finally got my harbor freight test gauge (#92699) hooked up to my fuel rail. (I guess the evap fittings aren't the same size as the fuel test fittings.... )

 

The gauge fittings worked just fine - no leaks that I could see. Here are my test values:

 

key on (cycled 3 times or so) 45 psi

engine on and running (idle) 50 psi

idling, with Vac. line on Fuel Pressure Regulator pulled : 58 psi

 

engine shut down: 45 psi

after ten minutes: 38-39 psi

 

This morning, at about -5 degrees F, I needed to cycle the key about 7 times before it would start.

 

I replaced the fuel pump with an "Airtex" about 1.5 months ago. I did not check the pressures at that time.

 

There was no fuel dripping from the vac line on the FPR.

 

I would guess the accuracy of the gauge as somewhat suspect, just from the cheap price of it.

 

I did replace the fuel filter at the time of the pump replacement, FWIW.

 

 

 

Bad FPR? I guess the way to check is to somehow block off the return hose and watch the fuel pressure, correct?

 

Bad Fuel Pump?

 

Thanks in advance,

[hrspwr]

Those pressure look good, the only one that I would like to see is when you cycle the key once. If it is not close to the 45 then it is likely that the FPR. To check to see if it is, take the return line to the tank off and set up a catch can/reroute the line so you can catch the fuel if any comes out. Cycle the key and see if the FPR is allowing fuel to go back to the tank.

[txab]

Pressure should be 55-62 according to specs, KOEO.

[mike g 09]

The gauge could be slightly off, but I bet it is only a few pounds - I tested it on my 97 chevy P/U, and it was about 60 lb with key on engine off.

 

Should I just replace the FPR and see what happens? Or attempt to shut off the return line and see what the pressures are first (to truly see if the FPR is the cause of the low pressures)?

[ChevyTech77]

Again, time for a pump. Buy a Delco this time.

[mike g 09]

That's what I was afraid of......

 

Again, time for a pump. Buy a Delco this time.

[Eddie 70]

I rented the Pressure Tester from Autozone. It was actually a very nice piece of equipment. Expensive to rent but it worked perfectly for me and I knew within 10 minutes of getting home with it and connecting it what was wrong with mine. Turned out to be a FPR also. The dealer replaced mine under factory 100k warranty. I don't know if they will do it for you since you have already been there. It does not hurt to ask though.

[mike g 09]

Is it possible that the Fuel Pressure Regulator is Bad, given my symptoms? I think it passed the "pulling the vacuum hose" test and the "fuel in the vacuum line" tests.

 

My only thought is that somehow it is regulating pressure on the low side, releasing it to the return line at a pressure below specificiation. The only way to test this, would be to pinch or shut off the return line, and see if the pressure goes up to 65 or so.

 

It sure would be an easier fix, but I don't know if it is the proper fix....