There are many reasons your carburetor may flood, but the basic idea is that fuel overflows the bowl. Fuel may come out the top of the carburetor if under enough pressure, or it may run down the throat of the carb and out around the throttle shaft.

NOTE: If you have any fuel coming out around the throttle shaft, the carburetor is flooding. This is not an indication of a ‘leaking’ throttle shaft. There should be no fuel sitting in the throttle body.

In no particular order, check these things

• Test your fuel pump. New fuel pumps are especially troublesome. Check your motors manual for the proper pressure, but for the AFB it should be around 5 lbs. Too much pressure will cause the needle not to shut off the gas. If your fuel pump is higher than 5psi, purchase an inline pressure regulator from your local parts store and install it between the fuel pump and carburetor.
• The needle & seat may be damaged. If while adjusting the float, pressure was put on the needle then it could easily have damaged the viton tip. If the needle is new, wipe the viton tip with mineral spirits to wipe off the black residue. Turn the top upside down and while the floats have the needles closed, blow into the fuel inlet (not too hard). Air should not get through. Test the Needle & Seat, or Float Valve.
• Make sure there is a gasket under the seat and there is only 1 gasket. We have seen old gaskets left behind, then a new one added on.
• Test your floats for leaks. Heat up some water and immerse the float. Bubbles would indicate a bad float.
• Check the float level.
• Your floats should be centered in the float bowls.
• Make sure there is clearance on each side of the float tangs.
• Move the float up and down to feel for any resistance, or catching.

• There may be dirt getting into the needle & seat holding the needle open. Filters may be dirty, or perhaps the fuel tank is dirty.