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Very Low Fuel Pressure #487384
10/03/09 07:02 PM
10/03/09 07:02 PM
Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
Mobarge Offline OP
pro stock
Mobarge  Offline OP
pro stock

Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
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?


'71 SSP - SOLD!
Re: Very Low Fuel Pressure [Re: Mobarge] #487385
10/03/09 07:03 PM
10/03/09 07:03 PM
Joined: Sep 2004
Posts: 6,906
IL, Aurora
A
ademon Offline
master
ademon  Offline
master
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
Worn pushrod maybe?

Re: Very Low Fuel Pressure [Re: ademon] #487386
10/03/09 07:05 PM
10/03/09 07:05 PM
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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ademon Offline
master
ademon  Offline
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IL, Aurora
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.

Re: Very Low Fuel Pressure [Re: ademon] #487387
10/03/09 07:27 PM
10/03/09 07:27 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
Circle Track
Happy Birthday RapidRobert  Offline
Circle Track

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Posts: 36,040
Lincoln Nebraska
Quote:

someone will chime in,


My new one is 3&7/32".


live every 24 hour block of time like it's your last day on earth
Re: Very Low Fuel Pressure [Re: RapidRobert] #487388
10/03/09 08:28 PM
10/03/09 08:28 PM
Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
Mobarge Offline OP
pro stock
Mobarge  Offline OP
pro stock

Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
Dumb question, but how do you pull the pump pushrod out? It's a 413 with about 2,000 miles on it.


'71 SSP - SOLD!
Re: Very Low Fuel Pressure [Re: Mobarge] #487389
10/03/09 08:35 PM
10/03/09 08:35 PM
Joined: Jan 2003
Posts: 5,270
Missouri
M
MY340 Offline
master
MY340  Offline
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Posts: 5,270
Missouri
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.


1970 FE5 Duster 360/904/3.91's SOLD 1973 TB3 SpaceDuster 340/4spd/4.10's SOLD Moparless for now but when the opportunity is right I'll have another one.
Re: Very Low Fuel Pressure [Re: MY340] #487390
10/03/09 08:43 PM
10/03/09 08:43 PM
Joined: Jan 2004
Posts: 9,066
Eugene, Oregon
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minivan Offline
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minivan  Offline
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Eugene, Oregon
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....

Re: Very Low Fuel Pressure [Re: Mobarge] #487391
10/03/09 08:51 PM
10/03/09 08:51 PM
Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
OzHemi Offline
Penguin-hating Ginger
OzHemi  Offline
Penguin-hating Ginger

Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
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.

Re: Very Low Fuel Pressure [Re: OzHemi] #487392
10/03/09 09:40 PM
10/03/09 09:40 PM
Joined: Jan 2003
Posts: 1,607
Lapeer, MI.
todd440 Offline
top fuel
todd440  Offline
top fuel

Joined: Jan 2003
Posts: 1,607
Lapeer, MI.
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.







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