Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Model number? Rider or push model? What engine?Briggs?
There is a solenoid, in the carburetor. It may be going out. It closes the main jet when it closes. That kills the engine. When you restart, it opens again, but is hot, so it runs shorter time!
It is anti-backfire solenoid. Older engines did not use it. No good test for it!
Mower has to have 12 volts to the solenoid, or engine dies! It can be removed and disabled, and re-installed as a dummy for test.
With voltage problem, is the charging system working?
The stator / alternator, is under the flywheel, and makes AC volts, it goes through a diode or rectifier/regulator to change to DC to charge the battery.
With voltmeter you can test the system.
Start at battery . Needs to be good battery. Battery voltage should be around 12. 5 volts. Then start engine and run at full speed, voltage should increase to over 13 volts.
If no increase, charging system is not working.
Stator output needs to be tested. AC volts need to be above 28 volts AC. If it is, stator is good, and problem will be with diodes or regulator.