B&S Push Mower Runs for a Bit then Shuts Down

[dorough]

I have a push mower with B&S Tecumseh engine that will run for about 15 minutes then sputter out of power and shut down. Restarting is virtually impossible without letting it cool down completely. Any ideas where I should start my inspection & repair?

 

[Fish]

I would suggest looking at the valves, put up some engine model numbers so we know what you have.