Charlie,
Make sure the gage is ok. Depressurize line to ensure gage goes to zero.
Hope this helps.
Good luck.




Joe D (The Frig)
1960 F-100 - 292 Y-Block
Philly Burbs

I pulled the plunger assy. from a used pump and here is what it looks like. There is a regulating system within the pump. I might add that the plunger needed to be coaxed with a strong magnet to get it to come out. Looks like a neoprene surface opposite the spring end so being exposed to our alcohol fuel may have a negative effect on these also.  This is a Holley branded pump but chances are, others may have a similar system.  It is, however, non adjustable, or,  at least not intended to be.  Good luck, JEFF..................


64F100 57FAIRLANE500

I did get a reply this morning from Carter that it is possible for this to happen if the internal regulator is stuck closed or mostly closed.
The question then becomes why isn't my Aeromotive regulator controlling the pressure to the carburetor.  Hope to hear from them today.  Maybe beyond some point, it can no longer control it.  Something I forgot to mention originally is that the pressure will not change with any change in the position of the regulator adjustment screw - it stays at 12psi no matter what.


Lawrenceville, GA

I agree that there is some kind of regulator or bypass valve in the electric fuel pump that is not functioning correctly.  I’ll suggest looking at the fuel pump first.

Lorena, Texas (South of Waco)

I don't use electric fuel pumps but I assume they have some type of pressure controlling relief valve and it may have been destroyed by the Ethonal fuel. Same with any other rubber carburetor parts. Over the last few years I have been having to replace, pumps, carb parts, fuel lines etc in all my old cars.

I've been having an intermittent issue with missfiring and one time an absolute lack of power.  Most of my ignition system was 10 years old and I did find some issues there and have corrected them.  Hoped that was it.  While checking timing after the install of the ignition stuff it would not idle well but it did eventually clear up.  The real short test drive went well and when I got to my driveway it was idling poorly again.

It seems to rev and hold higher rpm well well but won't idle well in the garage, no load.  It will stall unless I give it some throttle once in a while and is difficult to start if it does stall like it is flooding  So I pulled the aircleaner and looked down the venturis and found fuel coming from the passenger side primary booster, with the throttle closed, in the idle position.  Further, I turned the idle adjustment screws all the way in and it kept running.  So my thought is bad power valve or gasket or bad needle/seat assembly, or a sunken float.  I then unscrewed the sight plug and fuel poored out like a miniature fire hose for about half a second, seeming to support the bad float or needle idea.

Then I though "what about fuel pressure."  The pump is electric.  I checked that and 12psi is indicated on the gauge, the maximum of my regulator.  I tried another gauge and still 12psi so no issue with the gauge.  The problem there is that the fuel pump is rated for a 7-9psi but when I installed it, the most I could get was about 5psi so I'm confused about this 12psi indication. If I just let the pump run with the engine off, no fuel overflows anywhere,as if the needle seat, and float is working properly.

The carburetor is a Holley 570 Street Avenger, center hung float bowls.  I did remove the needle and seat assembly.  The o-ring looks grey and powder like on the outside, where it contacts the bore of the needle/seat cavity of the float bowl.  It looks like it may be cracked part of the way around the perimeter but it could also be a molding line from the original manufacturing of the o-ring as I don't know what these should look like when brand new.  The needle itself looks ok.  I don't really know what to look for but it looks good to me.  I can see where it contacts the seat but I don't think it looks significantly worn or anything like that.  The carburetor is about 10 years old at this point about July of 2009 that it was installed.

I didn't dig any deeper because I don't understand how there can be 12psi of pressure if the pump is not capable of that.  That must mean something.
Maybe if the pump was dead headed it could peak higher than it's rating?  But, particularly, if the engine is getting flooded at idle, and seems to rev and hold higher rpm, it wouldn't have that issue, right?

It seems like it may no longer be intermittent.  Hopefully it stays that way so I can get to the bottom of it.




Lawrenceville, GA