In my experience: The crankcase loads up with fuel when the needle and seat need replacement...or the float is stuck or has a hole in it. The fuel flow to the carb isn't being shut off when the bowl is full.
Not a difficult fix, In some older carbs, the seat is made of rubber and can be replaced. In newer ones, the needle has a rubber/nylon tip that seals against a metal or plastic seat, and only the needle is replaceable. Pull your carb, take the bowl off and give it a look. Also check the float to make sure it isn't punctured.
Soak in some carb cleaner, run a small wire through all the holes, blow out with compressed air, replace what's needed...I'm betting you'll be good to go!
Post questions if you need more help.
