This seems to be a recurring theme... ;-)
Best guess is a float valve stuck in the open position. Don't really need a carb rebuild, just a good cleaning.
Sometimes a sharp tap on the side of the float bowl will unstick the float.
Sometimes a treatment of Seafoam or Deep Creep will work.
Last resort is to disassemble the carb and clean.
See this thread for some tips.
Change your oil before you try to start your engine.
Someone probably needs to do a pictorial tutorial on carb cleaning.