Why will my Briggs and Stratton lawnmower motor start fine and then quit?

Your Briggs and Stratton lawnmower may start fine and then quit due to fuel issues, such as clogged fuel lines, a dirty fuel filter, or old fuel that has lost its potency. It could also be related to air flow problems, like a clogged air filter, or ignition issues, such as a faulty spark plug. Additionally, overheating due to low oil levels or a malfunctioning cooling system can cause the engine to shut down. Regular maintenance can help prevent these problems.