I have this Holley carburetor on a 292 in my '54 Mercury Convertible.  When this car was not in my possession it sat outside under a cover for over 7 years.  I got the engine started running it from a gas can but I have to prime it to restart it and it sputters and dies on quick acceleration.  I looked down the throat and I can see that the accelerator pump is not pumping streams of fuel down the throat when I open the throttle so it looks like the pump diaphragm is probably ruptured from age.  Can I just replace the pump diaphragm without doing a total carburetor rebuild?  Is just that part available and if so how can I know that I am buying the correct one for this carburetor?  Is the accelerator pump located inside that rectangular cover at the front of the carburetor?  Thanks

The accelerator pump is located under the front bowl.  It has a diaphram, spring, check ball, or rubber flap valve in the diaphram  housing.  The check ball needs .015" clearance between the ball and the wire holding it in place if that is the case.  The lever attached to the throttle linkage and the accelerator pump should have .015" clearance with the throttle blade positioned at wide open throttle.  The diaphram is available separately with its gasket, but the power valve is probably dried out and needs to be replaced, also.  That is inside the front bowl screwed into the main metering block.  Power valves are sold separately in some auto parts stores, but you will need gaskets if you open up the carb to look.  A complete carb rebuild kit will have all the necessary parts and instructions for float level, etc.  Joe-JDC

JDC

Thanks Joe but is sounds a bit complicated for me to deal with myself so I guess I will just take the carburetor off and bring it to the local carburetor shop.  

I just noticed that the arm on the linkage below the red spring that goes to the accelerator pump does not move when I manually open the linkage to full throttle.  I compared this to another similar Holley 4BBL carb. on another one of my cars and I can manually push down on that arm which makes the pump squirt gas down the bore as it should.  So it looks like the accelerator pump must be frozen.  What would cause that?

Diaphram is dried out and stiff, or the fuel in that housing has gunked up the check ball causing a fuel lock.  Also, check the plastic cam on the accelerator arm is in place and not cracked or broken.  If that plastic cam is missing, it will not actuate the arm.  Joe-JDC

JDC

I took the pump apart and the diaphragm looked good but there was a lot of loose debris particles in the pump housing and the small passageway looked blocked.  I cleaned it out with paperclip and blew compressed air into the hole and I also cleaned out the two holes in the nozzle.  The arm now moves the diaphragm  freely.  Put the carb. back on the car primed it to start it but still no gas coming out of the nozzle.  I think that there must be a lot of particles in the bowl and blocking the passageways.  Looks like I am going to have to take the carb. to the shop and see if they can just clean it out without doing a total rebuild as this was a brand new carb before the car was allowed to sit for seven years.

Suggest you take a good look at the gas tank as it may be the source of the garbage in the carb.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

I drained and flushed the tank before the first startup.  After the carb. is cleaned out I intend to use an inline fuel filter for awhile in addition to the one on the fuel pump.

Might not hurt to have that shop do a rebuild on it...  I've not seen one like that before- what's that goofy arm that goes to the black circle on the top of the float bowl?  Is that a 2bbl?

Under your choke blade is a bolt holding the sqirter.  It has two nozzles pointed at each venturi.  Remove that bold, turn the carb upside down and a needle will fall out.  Blow air through that and the nozzles, and the fuel should start flowing to the nozzles.  There are gaskets under the screw head and under the nozzle.  The one under the nozzle will be squeezed to the shape of the carb, and not flat.  Don't lose them.  If you get that far, then remove the jets and blow air through them, remove the power valve and see if it moves freely with a slight vacuum on one side.  It sounds like you have varnish/gunk build-up in the air/fuel passages that needs to be cleaned out thoroughly.  If you can't do that, then it would be prudent to have the carb boiled out with cleaner and a new gasket set installed.  A competent carb builder should be able to adjust the needles and secondary throttle blades to get a decent idle for you.  Joe-JDC

JDC