The symptoms seem fairly consistent with a floating fuel blockage upstream of the carburetor. I suggest you do Joe's test and find out if it will start and run very briefly if you put a spoonful of fuel into the carburetor intake or directly into the cylinder. If it does you've proved it is a fuel blockage. Try disconnecting the fuel line where it attaches to the carburetor, and see how long it takes to fill a cup with fuel, directly from the fuel line. If the fuel does not run full stream, clean out the tank, tap, filter if it has one, and fuel line so that you get full stream flow.
