Start by checking the fuel pressure, with the engine running on the fuel in the float bowl and the line to the carb deadheaded into a vacuum/pressure gauge. It should be no more than 4 PSI. Some rebuilders use a spring that's way too strong, and the fuel pressure overpowers the needle valve in the carb, causing a high fuel level and a flooding condition. The fuel pump am does not control the output pressure- - -the spring does that. Opening up the carb shows exactly nothing, because it's not the problem.
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!