VERY rough running engine!!

JRShaw

JRShaw

Senior Member
There is a newly rebuilt carburetor on my truck. When driven the engine comes very close to stalling, then running again at the last second. The surging is repeated again and again. When the engine is finally shut off there has been a loud "pop", possibly a backfire through the carburetor. Could this be a float bowl issue? Float set too high? NEED HELP PLEASE!! Thank You!!
 
If it does this while idling you can do this. Shut off the fuel valve and let it idle. If after a bit it begins running correctly before finally running out of fuel in the carb, float level may be the problem.
 
Another way to check the carburetor is to pull the choke out a little at a time. If the engine begins to run smoothly then the fuel mixture is too lean. Have you tried adjusting the idle mixture? Screwing the adjustment screw in on a Zenith carburetor will richen the mixture and screwing it out will lean it out. If too lean and the mixture screw does not help then the float may be too low so that not enough gasoline is in the float bowl. There could also be a clog in the carburetor somewhere. Dirt could have gotten in through the gasoline supply. Do you use an air filter? The Model A carburetor will not run correctly with an air filter.
 
Today I found out that the problem was a sticking bowl float. A few gentle taps with a small hammer (use a rag to protect the carburetor.) Thought that you would want to know.
 
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