* The engine is not getting enough fuel. This could be due to a dirty fuel filter, a clogged carburetor, or a faulty fuel pump.
* The engine is not getting enough air. This could be due to a dirty air filter, a blocked air intake, or a faulty throttle valve.
* The engine is overheating. This could be due to a lack of coolant, a faulty thermostat, or a blocked radiator.
* The spark plug is faulty. This could be due to a worn spark plug, a loose spark plug wire, or a faulty ignition coil.
If you are not able to identify and fix the problem yourself, you should take your mower to a qualified repair technician.