While you wait for answers, we may have found some information which could help you.
Click here for Engine Starts Runslawn mower won't start?
my briggs and stratton 3.5hp starts up then cuts out straight away?
lawn mower engine hunting?
lawn mower briggs and stratton classic 35?
Adding oil to mower ?
My Briggs & Stratton 10.5 engine will start but dies after about 15 mins?