Fuel Pressure Guage Virgin needs help

Reply Subscribe

Thread Tools

Search this Thread

Nov 28, 2007 | 07:05 PM

aj1988

Thread Starter

Melting Slicks

Joined: Mar 2002

Posts: 3,252

Likes: 6

From: The Colony Tx

Fuel Pressure Guage Virgin needs help

This weekend I bought a guage and today hooked it up. I sort of expected to see a reading just after making the connection. Guage showed 0lbs. Turned the key on and it jumped up to around 40lbs. As soon as the fp ended the cycle the pressure went back to 0.

I left the ignition off and went to check the connection to make sure there wasn't any fuel leaking out. The connection looked good so I started the car. The pressure immediately went to 42 lbs and when I reved the engine the pressure went from 38 to 42 lbs. Again, when I turned the key off the pressure went back to 0.

Is it possible that my guage has a problem? I did take the hose off and pushed the valve down. Gas came out so I know there is some pressure in the rail.

With the exception of a now very minor stumble off idle the car is running well. I am trying to narrow down the possible reasons for the stumble and checking the fuel pressure seems like a good place to start.

Nov 28, 2007 | 07:30 PM

Demonic85

Team Owner

Joined: Feb 2006

Posts: 24,460

Likes: 7

From: sw Ohio

Sounds like you could have a fuel pressure problem. How long does it take for the pressure to drop to zero after the fuel pump shuts off?

Nov 28, 2007 | 07:35 PM

aj1988

Thread Starter

Melting Slicks

Joined: Mar 2002

Posts: 3,252

Likes: 6

From: The Colony Tx

As soon as you turn the key off the pressure goes to 0. Just doesn't seem right. If there was actually 0 pressure I wouldn't think that pressing the valve would spray gas like it does.

Nov 28, 2007 | 07:42 PM

Demonic85

Team Owner

Joined: Feb 2006

Posts: 24,460

Likes: 7

From: sw Ohio

Sounds like something is wrong with your gauge then. There would have to be an open line somewhere for that quick of a loss and i'm pretty your would notice that.

Nov 28, 2007 | 07:49 PM

CFI-EFI

Race Director

Joined: Sep 2000

Posts: 17,298

Likes: 33

From: The Top of Utah

You have the classic fuel pressure bleed off problem that is very common. If there are no external leaks, there are three places the pressure can bleed from; leaky injector(s), fuel pressure regulator, or back into the tank via a bad check valve in the fuel pump, a bad pulsator or a leaky supply hose, inside the tank. You can isolate where the pressure is escaping by pressurizing and clamping off different hoses. The details should be in your FSM or you can find them by doing a search. It has been explained many times.

RACE ON!!!

Nov 28, 2007 | 07:53 PM

Demonic85

Team Owner

Joined: Feb 2006

Posts: 24,460

Likes: 7

From: sw Ohio

From the FSM:

1. Turn ignition on and pinch the fuel flex hose (look under the AC compressor and you will see these two hoses). The pressure should hold. If it does its a leaking pulsator or bad fuel pump.

2. If it doesnt hold, pinch the flex hose return line. If it holds pressure, its a faulty pressure regulator. If not then its the injectors.

Nov 28, 2007 | 09:09 PM

aj1988

Thread Starter

Melting Slicks

Joined: Mar 2002

Posts: 3,252

Likes: 6

From: The Colony Tx

Apparently paitence is not one of my major virtues. I hooked the guage up about an hour ago and started the car. The pressure came up like the first time and when I shut it off it dropped again. But, this time I didn't take the guage off. I went out a little while ago to check the timing and suprise, the guage read 42 lbs. I guess it just needed time to figure out what it was supposed to do.

Thanks for the replies. I set the timing to 6 degrees and the stumble is still there. Now to keep looking for the problem.