Small Engines (Lawn Mowers, etc.): Sears Craftman lt 4000 Briggs and Straton Engine, sears craftman, crankcase oil

Question
Ths issue is that the oil is smelling like it may have fuel in it.  The lawnmower won't start up and has been having some minor intermittent problems here and there to get it to start and stay running with a big poof of white smoke coming out of it at least once.  Is there some kind of oil buildup within the engine that could be causing these issues?  I have very little time to troubleshoot too much and really need to get the riding mower running...

Answer
 Hello Norm:

 Over the Years this has Become a Common Problem. Here are 3 Things to Correct it. 1- Rebuild the Carburetor. The Float Needle Isnt Seating Properly and the Gas is Flooding the Cylinder and Seeping Into the Crankcase Oil. 2- Install a Manual Cutoff in the Gas Line and Turn of the Gas Flow when the Engine is Not in Use. 3- Change the Oil. Hope this Helps. I am here if you Require More Assistance. Thanks.

 Good Luck

 Respectfully

 John