Very Low Fuel Pressure

Posted By: Mobarge

Very Low Fuel Pressure - 10/03/09 11:02 PM

Noticed something interesting today during a nice, leisurely morning drive.

I have a gauge on my Russell fuel feed to my carb. The gauge is about six months old. At idle (900 RPM), the gauge reads that my fuel pressure is 1 PSI. When I wrap up the RPMs (to around 3,000), it reads 3 PSI, so I know the gauge works.

The car runs and idles fine... although, I did notice it wanting to peter out when I landed on it.

Bad fuel pump? I am running an Edelbrock mechanical fuel gauge, 120 GPH at 6 - 8 PSI (supposedly). Pump is a few years old. Could it be the diaphragm?

Posted By: ademon

Re: Very Low Fuel Pressure - 10/03/09 11:03 PM

Worn pushrod maybe?

Posted By: ademon

Re: Very Low Fuel Pressure - 10/03/09 11:05 PM

pull the pump and check the length, i forgot how long it should be someone will chime in, but if its worn you will also see it concaved usually on the cam end.

Posted By: RapidRobert

Re: Very Low Fuel Pressure - 10/03/09 11:27 PM

Quote:

someone will chime in,

My new one is 3&7/32".

Posted By: Mobarge

Re: Very Low Fuel Pressure - 10/04/09 12:28 AM

Dumb question, but how do you pull the pump pushrod out? It's a 413 with about 2,000 miles on it.

Posted By: MY340

Re: Very Low Fuel Pressure - 10/04/09 12:35 AM

A leak/air entering in the fuel line will also cause low fuel pressure. On my old Duster mine was back by the fuel tank and the hose didn't leak fuel. It gave me fits for about 3-4 weeks before I figured it out.

Posted By: minivan

Re: Very Low Fuel Pressure - 10/04/09 12:43 AM

Quote:

A leak/air entering in the fuel line will also cause low fuel pressure. On my old Duster mine was back by the fuel tank and the hose didn't leak fuel. It gave me fits for about 3-4 weeks before I figured it out.

A hard gremlin to chase.. The fuel line is sucking from there and will not leak but allow air to enter from the suction of the fuel pump.. Your looking for fuel leaking when its air being sucked in....

Posted By: OzHemi

Re: Very Low Fuel Pressure - 10/04/09 12:51 AM

Quote:

Dumb question, but how do you pull the pump pushrod out? It's a 413 with about 2,000 miles on it.

You pull the fuel pump, and there is a pipe plug just under it, remove that and the push rod will slide out.

As said, a hose sucking air could be an issue too...check all the stuff in the engine bay and the bit at the sending unit too just incase.

Posted By: todd440

Re: Very Low Fuel Pressure - 10/04/09 01:40 AM

I've noticed a rash of worn pushrods lately, probably due to the lack of zinc in the oil. I have about 10 on the bench right now, most are worn, 1 of them a full .250 short of a new one. Look for a worn or cupped tip.