Fuel Pressure Regulator

[fast95orange]

My car is running really lean. Like hitting 17.5 on the wideband. I have been doing a lot of checks and I have narrowed it down to two things. Let me get this straight:

1) The fuel press reg maintains constant pressure in the fuel rail. The excess in redirected back to the tank through a return line off the regulator. IF the diaphragm in the regulator is torn, the fuel would simply remain low pressure in the rail and the excess would go out the vacuum line on the regulator dumping into the manifold? Is this right?

2) Cause my car has a liquid gas smell. I have checked underneath for physical leaks but I don't see any clean areas from the gasoline or any drips that I might see before it evaps.

The other possibility is my fuel pump. However when I turn the key, I hear the pump prime. Could it be electronically functional but mechanically broken? i.e. not being able to keep up with the engine's demand at higher rpms?

Thanks a lot

[Paulster2]

Have you put a gauge on it to check what the fuel pressure is? I wouldn't be changing any parts until you get that figured out.

To answer your questions:

1) If the diaphragm was torn and leaking into your vacuum line, you would be running rich, not lean, because the vacuum will suck the gas into the engine and (try to) burn it.

2) Is your gas cap sealing all the way? Is your evap system working correctly?

3) Yes, that is why you need to put a fuel pressure gauge on the Schrader valve and see what's what.

[95z28onjuice]

Must hook up a gauge or its just a guess my friend. if the pump is making any sound most of the time its working, if you pull the vac line off regulator and there is gas in it you need a reg to start. but all and all you need to hook a gauge up and see what its doing with vac and vac disconnected.

[fast95orange]

Alright, sorry I forgot to say that it reads 40psi constant on the gauge. I unplugged the vacuum line on the regulator and it is still running lean. I have an air/fuel module in my car and at start up it reads stoich. Then when I get on the throttle it goes lean off the scale. However, when I hook up the fuel gauge in my driveway and car isn't under load, despite revving the engine, it remains at 40psi. The only thing I can think of is to snake the fuel pressure gauge into the cab somehow and measure the pressure while I'm driving the car and engine is under load..

Any suggestions?

[Blown1993Z28]

Originally Posted by fast95orange

The only thing I can think of is to snake the fuel pressure gauge into the cab somehow and measure the pressure while I'm driving the car and engine is under load..

Any suggestions?

Just run the gauge out of the hood area next to the windsheild. Then tape it to the windsheild from the outside where you can see it while driving. Does your fuel:air monitor have a capture function?