There are many reasons your carburetor is flooding. Flooding means fuel is overflowing over the top of the carburetor. Running rich means the exhaust has black smoke, or there is a strong smell of gas.
- 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.
- 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.
- 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.
Flooding can be summed up with one idea. Too much fuel is getting into the float bowl.