Re: Gas blows out of vent hole
That carb has a little flapper valve gasket thing behind the fuel inlet cover. It also has a bladder-type fuel pump element that inserts into the carburetor on the flange that mounts to the engine.
If the bladder has a hole in it, compressed fuel/air mixture will enter the carb from the crankcase, causing your situation. If the flapper valve is torn, weak, or missing, the same thing will result, except caused by fuel entering the wrong passage from the bladder.
Both parts are available from certifiedpartscorp.com, and the nice man there can make you a complete carb kit. You'll have to call the phone number on the website, though, since the parts aren't listed.
