This is on my 55. It has had three rebuilds of the 4GC carburetor and the last two haven't lasted more than 3000 miles before the accelerator pumps become swollen, distorted and I pick up the dreaded bog on takeoff .The same thing has happened again. The accelerator pump material is marketed as a alcohol resistance material but it is reacting as though it isn't. My question is does anyone know of a known good manufacture and part number for a accelerator pump replacement that will hold up. The last three all have been of a medium blue in color...... Thanks in advance.... Tedd

 

There:

The one I have in my 54 came in a kit from Fusick. It is about two years old and so far so good. I don't think they have them separately. And they are blue.

 

NAPA sells the accelerator pump for the later QJets (later as in my '71). They are a blue color and the one in my carb has been OK for more years than I can remember. I don't know if they carry them for the 4GC, though.

edit: I did a quick search and found this site that sells ethanol resistant accelerator pump cups for ~$3 each:

Rochester 4G Carburetor Accelerator Pumps
http://quadrajetparts.com/accelerato...c-104_109.html

Get a pump cup and an air horn gasket and you should be able to fix that carb fairly easily and cheaply.

 

Thanks all, working on it as right now. It appears that there are two types of blue cups and two diamatier cup sizes this may be the problem.... Tedd

 

Tedd,

Over here, Hobbs Carburetor in Pelham NH is legendary. Why not give them a call at 603-635-2415 and ask for their advice.

Their address and phone number is on a nail at every auto parts store in New England.

 

Got it back together with a different color(dark blue) accelerator pump cap I'll see how that works. I'll give it a test run tomorrow. Also had to replace the battery that had a melt down and caused me to come home on the hook last week.....Tedd

 

I would also consider using an ethanol treatment with my gas, Lucas and Sta-bil have them.

 

I think the problem is too much ethanol already and this car gets run at this time of the year most every week for a hundred miles or more.What would Sta-bil do in keeping the accelerator pump cups from turning to mush, a'm
I missing something here?.....Tedd

 

The treatments counter the effects of ethanol in your fuel system, which deteriorates your soft lines and any rubber components in your carb, including gaskets. Ethanol will also corrode your gas tank due to the moisture that occurs from it's use. Hopefully someone here that can explain it better than me, will chime in.

 

Various Gas Stations around me offer Ethanol free 91 & 93. But you gota look for it. Everything I have with a carb even the 95 injected GC Jeep gets ethanol free.

 

There hasn't been ethanol free gas around here for about 7 years unless I want to spring for race gas. I don't see a need as I nor anyone else has run into any issues. Glad you might have it fixed Tedd.

 

Well it's BACK! Not as bad as before but definitely still there. Worse when engine is cold and why that would make a difference, confused. I'm looking for another problem other than just the accelerator pump, maybe accelerator pump is kicking in just a little late giving the carburetor a lean condition for a second or two.Don't know and it's too hot to work on today (108 degrees right now).I have to think about this over night.

Just got back from a car show in Oroville Ca. and got lucky and made one of the top 10 car awards. Probably 200 + cars..... Tedd