Maybe a collapsed float. Sometimes a backfire puts enough pressure into the float bowl to damage or collapse a hollow brass float. How much effort would it be to pull the top off the carb and inspect the condition of the float?
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!