Small Engines (Lawn Mowers, etc.): Backfiring, craftsman lawn tractor, crankcase oil

Question
Hi John,

I have a 42" Craftsman lawn tractor with a 17 HP kohler CV490S engine.  The engine will not start and when it turns over there is an occasional backfire. Smoke come out of the exhaust.  At first, there was some fuel coming out of the exhaust but I took apart the carburator and cleaned it with Gumout.  Now there is now fuel visible but I still get the occasional backfire when I turn the engine over.  What should I do?  Thank you in advance.

Answer
 Hello Jim:

 Check the Engine Oil. Does it Smell Of Gas? Drain it and Allow the Crankcase to Repain Empty Overnight with the Fill Cap and Drain Plug(if it has one) Left Out. Replace the Drain Plug and Fill to Proper Level with Oil. With the Spark Plug Out, Turn the Engine Several Times. Replace the Spark Plug and Try to Start the Engine. The Carburator Float Needle Allowed the Engine to Flood and the Cylinder Filled with Gas. The Gas Leaked by the Rings and Contanimated the Crankcase Oil. Install a Cutoff Valve in the Gas Line and Turn the Gas Flow Off when Not Using the Mower. Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John