John..

I put an adjustable pressure regulator and pressure damper on my car. When I changed all of this stuff, I noticed there was no fuel pressure in the system. The car started fine, ran fine, then I lowered my pressure to 30 psig to lean out my mixture because I have very high flow injectors in the car.

Well, the car loses all fuel pressure once it is turned off (about an hour or so after sitting). On cold starts, it fires right up like it always does.

I am having problems with warm-hot restarts...like after the car sits for 30-45 minutes after shutdown.

Thinking it was the check valve in the fuel pump, I replaced it, with no change....! Good thing it is only $17.00


Could I have a leaking injector somewhere?

Where else could the system be losing pressure? I do not smell gasoline or have any leaks anywhere, and I am sure it has always been losing pressure (since when I changed the regulators there was no fuel pressure).

Any thoughts?

WallyP

Your symptoms are consistent with a leak into the intake system. When the engine is hot, and the fuel slowly leaks into the intake, the engine will be "flooded", that is, there is too much fuel for the amount of air. After the engine is cold, the extra fuel helps the start. I would expect it to be a bit hard to start after several days, as the leaked fuel totally disappears, ant the mixture will be lean on startup.

There are a limited number of places that the fuel can leak into the manifold.

The pressure regulator has a vacuum connection so that the fuel pressure can be increased on low vacuum/open throttle conditions.

Each of the fuel pressure dampeners has a vacuum line, just as a safety measure in case the diaphragm leaks, so that leaking fuel will go into the intake, rather than onto the engine.

And, of course, you have eight injectors (nine on the early cars) that are possible leak sources.

Pull the vacuum lines at the regulator and dampeners, and check carefully for any trace of fuel. You might want to cautiously run the engine for a few minutes to see if any fuel comes from the units, but be very careful if you do this. Spraying gasoline over an engine is not really a good thing.

If there is no trace of fuel from these units, an injector is the next obvious suspect.

John..

Thanks Wally,

That was what I was thinking would be the next step to look for. The regulaors are new, and the old ones did the same thing, so I do think it is an injector. My car has 11 (10 for running and one cold start). I'll start by blocking off the two that enter into the air-stream for on-boost conditions. I have a feeling these are suspect right now.

Mike Schmidt

Check the oil dipstick to see if there's a strong gas smell. If an injector is leaking gas will enter the engine and end up in the oil.