Holley 1940 Accelerator Pump Circuit Problem

Rebuilt the carb, ran great for a few minutes then the RPM’S dropped and now all I can get is a dribble of gas when hitting the throttle. Not sure what’s going on. Any suggestions. Ill pull the carb off and pull it back apart. When it’s cold and you hit the throttle all I get is a dribble running down the inside, no squirt of fuel.


Most likely the problem is in the accelerator pump circuit. Did you run thin wire through all of the passages, especially at the main discharge? Ethanol leaves deposits behind that cleaners can’t remove. If you pump the throttle linkage and don’t see gas squirting into the venturi, then you have a blockage somewhere.

Follow Up:

Holley 1940 CarburetorHolley 1940 Carburetor


I believe I have it fixed. I was watching the accelerator pump rod while moving the throttle by hand and the pump rod was not moving. The 1940 has that triangle piece mounted to the front of the carb with the 3 slots in it. When  i actuated the pump rod by hand the car ran perfect. So i took the carb back off to see if the pump piston was hanging up. Everything looked good, other then the movement of the pump being really “stiff”. I cleaned and checked the accelerator rod for nicks or burrs and it was fine. The piston is a lot bigger in diameter then the one I pulled out. I guessing mine had shrunk over time. I put the carb back together, sprayed the outer linkage with silicon spray and just kept working the pump by hand until it got easier. Put it back on the car and its been running good, very smooth idle, no leaks. I still have to drive the car and check it all out.



I hope you are doing fine, I just send you an order to your webpage # 10983, because we need to repair the carburetor installed in our Hobart JET EX II generator, the manual of the generator says that the carburetor is a Holley 1940 D7JL-9510 A , however the plate say motorcraft but the part numbers are matching, so I am attaching you a couple of pictures for your info. Just in case I ordered another stuuf that is not going to work, please give me your assessment on this one.


Holley made the 1940 for Motorcraft and many of the 1940 1 barrel carburetors will have a Motorcraft tag even tough they are really a Holley. It is the same carburetor and all that really matters is the carburetor number. In your case the D7JL is what you should match in the list of carburetor numbers for any particular kit.