Fuel Pressure Testing

[Havoc]

Hi Everyone,
I have a 93 2.3L Quad 4 OHC 137,000 miles, and I wanted to know how can I check the fuel pressure. I purchased a Chilton's Manual, and it said that on most models there is a valve on the fuel rail to test the pressure. I do not see a valve on the fuel rail anywhere. The car has a problem starting and staying running no longer than a few seconds. Turning the key, I can hear the Pump prime. I have replaced plugs, coils, coil housing and fuel filter. The Ignition Coil Module was tested to be in good working condition. Any Suggestions would be greatly appreciated.

Thanks.

[rixGAphx]

I've read on this board that many 4-cyls do NOT have a pressure test port.

Sounds like you're on the right track.

The fuel pump is a vane-type (not old-fashined diaphragm type).
It may be fine as far as turning goes, but the seals on the vanes eventually wear and will no longer hold pressure.

I *think* you also have a fuel pressure regulator at the inlet of the fuel tube to the fuel rail; it may be broken (when it fails, it *should* shut-off rather than stick open), so that might also be the fault location.

Sorry, I don't know the pressure test procedure.

Good luck.
-Rick

[Havoc]

Thanks!!
A new Fuel Pump is $80, A new Regualtor is another $80. What's the best place to start? I don't think I can return either one to the store.

[Havoc]

Thanks,
New Pump $80, new Regulator $70. What's the best place to start? I don't think I can return either one to the store.

[rixGAphx]

I think I would disconnect the fuel inlet pipe to the regulator, and get a piece of fuel injection hose to clamp onto the tube end.
Then get a gage and some adapter tubing/threaded fitting to slip on the open end.
I could thusly test the pressure from the pump.

If pressure is bad, then replace pump.
If pressure is good, then replace the regulator.

In any case, the regulator is a A LOT easier to replace than the FP, which is located inside the fuel tank.

Good luck.
-Rick

[Brad97GS]

That's right Rick. The newer Quad 4s don't have the Schrader valve for some reason. My old '89 did, but I think around '92 they did away with them. IIRC, your procedure for testing the fuel pressure is the way to go. Kinda crummy, but whatever works. :)

I have heard of a test for the regulator that is quite simple. There is a vacuum line running from the regulator to the intake manifold. If you pull off that line with the car running, and gasoline is running out of the line, then you have a bad regulator. I would say that if there isn't gas coming out, it doesn't necessarily mean the regulator is okay, however.