Gas is coming over the top, leaking out of the throttle shaft, or coming out of the vent.
Flooding means there is too much fuel getting into the carburetor.
There are many things that could be causing this. Here is a list of things to check, not in any order.
- Most flooding problems are centered around the needle & seat. Dirt particles get into the seat keeping the needle from sealing. Perhaps the viton tip is damaged. This is easy to do when adjusting the float. No pressure should be put on the needle as it is easily damaged. Try blowing a small amount of air into the inlet. This might dislodge any dirt. Many good rebuilds go bad due to a dirty gas tank. Ethanol tends to clean residue that has built up in the gas tank over many years. The particles then end up in the carburetor. Even an in-line gas filter won't keep everything out.
- The gas may have turned leaving a film of varnish on the internal parts. If the engine has been sitting for more than 3 months, this would be very suspect.
- Fuel pump pressure may be too high. New fuel pumps are especially suspect. Refer to your motors manual for the correct pressure, but about 4 lbs would probably be OK. Sometimes installing a regulator between the fuel pump and carburetor might be the answer.
- Float has a leak - heat up some water just prior to boiling and immerse the float. As the inside of the float heats up and expands, any leaks will show up as bubbles.
- Move the float up and down to be sure it isn't rubbing, or the pin is so worn that it's binding.
- Float Level - Set it to specifications. Don't fudge it to get it to quit flooding. You are just hiding the real problem.
- Power valve stuck open. The power valve adds extra fuel at higher RPM's. If stuck open, too much fuel will be fed when below power RPM.