I have a 73 350sbc in my 67 and I run an Edelbrock fuel pump. The fuel pressure jumps all around from 9 down to 3 to 6. This is the second pump. I called Edelbrock and they said that it sounded like it was a bad fuel pump because the first one I had was reading 12 or so. I returned that one and got this one. Both of them came from Summit. Is it possible that they had a bad batch of pumps? Anyone experience this with this brand of pump? Edelbrock said it should put out between 5 and 7psi. I am not sure what to do. You can smell gas out the exhaust and the gauge gives numberous readings. I am using a Mallory liquid filled gauge plugged into the fuel inlet. This is also the secong gauge. The first one wasn't liquid filled and it bounced all around also. Any suggestions??? Thanks in advance.

Does anyone have any ideas??

is it electric, or mech???a mech pump will surge with cam rotation, but should be less noticeable with a liquid filled guage(still shouldnt be a variance of more than 1 lb)...a elec will give steady readings...the fluctuation could also be caused by bad needle and seats...when the seat opens, pressure in the line will drop...disconnect the feed line to the carb, and plug both ends solid...then read pressure...if it stabilizes, your problem is in the carb...if not, the pump is the culprit...

What do I use to plug it? I am using the Edelbrock braided stainless line from the pump and then it has the Edelbrock hard "L" shaped hard line with the chrome fuel filter.

low pressure...plug it with your thumb if nessecary...or take the braided line off, and connect a rubber hose with a bolt in it...

Check this out. Yesterday I was tuning the idle mixture screws and the car was idling for a while. When I looked at the fuel pressure gauge, it was on zero. How is this possible? It is a brand new gauge. The one I had before it did the same thing. I removed it and noticed a screw inside the threads. I turned in the screw and the gauge read higher. Was I suppose to turn that screw? How do I know the pressure is actually what it is reading now? I am lost. How can a car run with 0 fuel pressure?

The gauge is broke. The screw inside is to calibrate the gauge. Or fuel pump ain't working or fuel line from tank is plugged or gas cap is not venting.

If engine is running for longer than 5 minutes, then I'd say the fuel system is working, gauge is broke. If you were to relocate the gauge and run a pressure line to the gauge, the gauge would last longer. Vibration kills them.

The gauge is brand new. It didn't have any time on it at all. I took it straight out of the box and onto the car. If the line was plugged wouldn't the pressure be low all the time? Not just after a long idle? When I first start the car up in the morning the pressure is good. It's only after the car has been idling for a while that the pressure drops. I removed the gas cap and the pressure didn't change at all. I can't see three gauges being bad.

Check this out. Yesterday I was tuning the idle mixture screws and the car was idling for a while. When I looked at the fuel pressure gauge, it was on zero. How is this possible? It is a brand new gauge. The one I had before it did the same thing. I removed it and noticed a screw inside the threads. I turned in the screw and the gauge read higher. Was I suppose to turn that screw? How do I know the pressure is actually what it is reading now? I am lost. How can a car run with 0 fuel pressure?

You'd be surprised how far and fast you can go on very little fuel pressure. We were road racing in Mexico a few years ago and had an electric fuel pump failure early Sunday morning in downtown Mexico City. A desperate search which included a lights-and-siren run with a Mexico City policeman produced an electric pump from a small Onan generator with 1/8" pipe fittings. We wired this thing up under the car and took off, about an hour behind the rest of the cars. With virtually no pressure reading on the gauge we were able to maintain speeds in excess of 100 mph and only lost about a minute to the second place car.

Hook up a commercial-quality gauge for testing the fuel pump. Those inline gauges are junk. I've had a few different inline gauges and they've all malfunctioned. Useless junk IMO.........................

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Don't trust the gauge.:cool:

You could also rule out clogs, vent & tank issues by temporarily running a ruber gas line from the pump inlet to a gas can to see if the problem goes away.

Over the weekend I was thinking that if there really was a pressure problem, wouldn't WOT be affected? The car pulls all the way to the rev limiter.

Yes, WOT would be affected, more pronounced in 3rd, especially in 4th, or higher gear as fuel would run out.

Greater load, read more wind resistance, more fuel required to move car through the air.

I am leaning toward the gauge needing to have the internal pressure equalized as ORENCH said. I am going to try that.

I also forgot to add that the tank and sending unit is brand new.

I think it may just be the gauge internal pressure needing to be equalized. Thanks for all your help and suggestions.