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1971 Ford Thunderbird. Just rebuilt the engine. Rebuilt carb. Having the same problem. Starts and drives fine until I accelerate heavily, (before the four barrel kicks in.) and the car stalls. Sit for a minute and pump the gas and the car starts. Guessing something from the fuel supply. Anybody can tell me what to expect when dropping the tank? Could it be the Fuel Vapor Separator needs replacing or something getting pick up in the tank? I did replace the fuel tank gas cap.
did you try running it with a old cap with a 1/4 to 5/16 hole drilled thru it ? i do not know if you can do this on your car if the filler neck is hi like in the rear 1/4 them you can try it see if it still will do it .if not then it a vent deal. drill the hole in the cap off the car......... or the pick up in the tank on some cars have a filter on the pickup
Ended up taking out the gas tank. Tank was clean. Lines where clean. Still stalls when accelerating. Idles fine. New rebuilt engine. Rebuilt carb by Pony Carb. New fuel pump.
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Is the fuel tank properly vented??? This is what Pat was alluding to in his post above. Sometimes as fuel is drained from the tank, a vaccum forms that prevents the flow of fueln from the tank tot he carburetor. Therefore, try running the car without the fuel cap installed and see if the probelm persists. If the problem away, then you need a vented fuel cap. If the problem persists, then you have eliminated one possiblity and we'll move on from there.
Paul
Paul, Thanks for the reply. Keep in mind I have been trying get this engine to run for the last two years. When I first got the car it ran fine. One day I jumped on it and heard a "pop" or misfire through the carburetor (Im guessing). Then the problem started. Since then I have:
Professionally rebuilt the engine.
Rebuilt Carburetor by Pony Carburetor.
Everything is new on the engine.
Engine runs great until I accelerate heavily. Then it stalls. Pump the gas and it starts.
If I drive at 25 to 35 its fine.
Fuel pressure nine to ten pounds.
Temperature around 200. Never overheats.
When it does stall I hear what sounds like gas flowing into the carburetor or the gas is boiling in the carburetor. When I shoot some fuel into the carb during the stall it sounds and looks like it evaporates. The carb also overflows.
This problem has been persistent with the old engine and then rebuilt engine along with two rebuilds of the original carb.
This has puzzled every local mechanic.