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