Your float valve is stuck open. Probably some debris under the float valve. You'll have to take the carb off and clean it good. Clean the float valve and valve seat, but I would clean the whole carb while I had it off, jets and all.
If it's the float sticking, sometimes you can tap the carb bowl with something and jar it and it will quick leaking, but it's just a temporary fix if it works, but that would tell you that it is the float.