First, get the engine idling with the air cleaner off, and look down into the top of the carburetor with a bright flashlight. If fuel is dribbling out of the venturi area, about the middle of the carb body, it's flooding. Look for a hole in the float, or dirt between the needle valve and the seat area, where the fuel enters the carb. The float and the needle valve work just like the ballcock valve in a toilet, they're supposed to maintain a stable fuel level just below the point where the gas can overflow into the air stream. Most likely, you've got dirt in the fuel, and even a tiny piece of debris can cause the carb to flood. Get the carb clean, and install a good inline fuel filter to trap the crud before it reaches the carb. Worst-case scenario, pull the fuel tank and have it cleaned by a radiator shop, or replace the tank if it's really in bad shape!
Jerry
