Small Engines (Lawn Mowers, etc.): lawn mower wont stay running, air filter assembly, starter rope

Question
my lawn mower is a Troy Bilt with B&S engine model # 12AI869F011
the first time I pull the starter cable the lawn mower sputters for 3 seconds then dies, when I pull the starter rope again nothing happens. the only thing that will make the lawn mower sputters again for another 3 seconds and dies again is if I remove the breather tube from the air filter assembly and reattached it again. Gas has been replaced with fresh gas, oil drained and replaced with new oil, spark plug had black and I can smell gas in it.

Answer
The condition you described is very common.  Have you drained the carburetor fuel bowl or cleaned the carburetor?  Sometimes just removing the carburetor float bowl nut, on the bottom of the carb, and draining the gas from the carb will fix the problem.  

Make sure the float bowl nut holes are clean.

Let me know if draining the carb fixes the problem.

Eric