Small Engines (Lawn Mowers, etc.): B&S Engine starts hard, wont run, carburator, exhaust air

Question
B&S Model 28b702, Type 1143E1, Code 980619za

Engine starts hard, like 10 to 15 pulls.  When it does start only runs a few minutes, then quits.  Black smoke belching from the exhaust.  Air cleaner oil soaked although not otherwise dust or grass-clogged.

Recently repaired loose belt and had to tip mower up causing oil to come out exhaust however it has run ok between then and this latest malfunction.

Replaced spark plug but no help.  When I take the air cleaner off completely, seems to run ok.

Thanks for your service.

Answer
 Hello Ed:

 From your Description I Suggest the Carburator be Cleaned and Rebuilt. The Carburator Float Needle is Sticking and Flooding the Engine. Also Clean the Crankcase Vent of Oil. You can View a Breakdown of this Engine and Carburator at this Addy http://shop.briggsandstratton.com/BShopProductListingPage.asp?rsvp=0&PARENTID=0&... and Enter the Model Numbers 28B702 and the Type Numbers 1143 and Search. Then Scroll Down to the 2nd Listing and Click on View PDF. This will DOwnload a Breakdown of the Carburator anf Engine Online. Hope thia Helps. I am here if you Require more Assistance. Let me know what Happens, Please. I enjoy knowing the Outcome. Thanks.

 Good Luck

 Respectfully

 John