Small Engines (Lawn Mowers, etc.): gasoline came out of the muffler and oil plug on a Tecumseh 12HP, oil drain plug, engine crankcase

Question
Gasoline came out of the muffler from a 12HP Tecumseh engine when I tried to start it.  Also, gas came out of the oil drain plug when I attempted to change the oil.  The engine didn's start.  Is this bad or is the engine ruined?

Answer
This is fairly common.  The inlet needle in the carburetor did not stop fuel flow correctly allowing gasoline to enter the engine crankcase through the intake valve.  

To solve your problem, remove the spark plug.  Crank the engine with the spark plug removed to clean the cylinder.  Drain the oil.  Refill the oil.  Replace plug and try to start.

It is possible for the inlet needles to just leak once in a while, but if you brought the mower into the shop we would flush the fuel system, clean the carburetor and replace the inlet needle and seat.  

Let me know if you have any other questions.
Eric