I posted a while ago about the fuel pressure readings on my system. I have a 454 with a 4150 on it. I added a nice looking fuel log with -8AN (big) fittings and a pressure gauge right before the log. I also replaced the electronic fuel pump, and put on a 12-454 Holley mechanical, which is supposed to run at 6 to 9 PSI.

When I start the car, I get 8 PSI. As the engine heats up, the pressure drops to 2-3. Yesterday, it was at 0 psi, but the car still ran fine. I have replaced the gauge, the new run reads the same way. I replaced the pump, and the readings still read low with any combo of pump and gauge. But the car has never coughed.

Any guesses? The big Fram canister filter is clean, and all the fuel lines are new. I am wondering if there is junk in the tank, and as I drive, it gets stirred up and sucks onto the pickup tube sock, if there is a sock (?) in the tank.

Help?

Gib,
Try a regular size mechanical gauge, just for a test. Any gauge will work, even oil pressure. Actually, the best thing to do is get a large combination fuel pressure / vacuum gauge and use it to set the pressure. Once you set the regulator, take the gauge out, you cant see it anyway with the hood closed ! I have seen a bunch of the small (1" or so) gauges fail almost from the start. It seems that the only ones that last are the liquid filled ones and they are even questionable. If the car is running ok, you must have fuel pressure. I recently helped a friend with the same problem and we sent back 4 gauges before we go two that would work.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

While what Bill says is true, I've had a Summit (Holley) regulator and Summit fuel pressure gauge on my car for about 5/6 years now with no problems. It's true I can't see the gauge from within the car, but it helps to know it's there when I'm working on the engine. It's mounted in-line with standard 3/8" fuel hose and rests on the heater core box.

The car had been apart for about a year and I just got it running a few weeks ago. The gauge saved me in this instance. It seems as though the mechanical fuel pump had decided not to work any longer and I spent a couple of hours checking timing, plug wires, etc when it wouldn't run. Happen to look up at the gauge and, viola, no fuel pressure. Bolted on a new fuel pump and she fired right up.

I've also had occasion to notice that when the fuel pressure drops from 7lbs to 0lbs too quickly after shutting the engine off, I had bad or dirty needles/seats. When pressure dropped to zero almost immediately after shutting down, I knew I was losing the pressure somewhere and the needles/seats were the culprits.

To each their own, but that's my war story on fuel pressure regulators and gauges.

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Dale McIntosh
ACES #1709
Team Chevelle #92 Gold