The problem is a bit of trash is preventing the float needle from closing fully to stop the flow of gas. Try this; drain the float bowl then close the drain and turn on the gas. Tap the float bowl solidly with the end of a screwdriver handle. The object is to free up the float / shake loose the trash. If doing that a couple of times does not fix the problem, Remove the float bowl and spray the interior of the carb using spray carb cleaner. Pay special attention to the float pin area. With the float bowl off you should be able to gently lift and lower the float. Lifting should shut off the gas and lowering should let the gas flow again. If the float shuts off the gas when raised, put the float bowl back in place and see if the carb still over fills. If so, then the float is defective and you will need a new one. Please rate my answer. Thanks.