I have a Scotts Turf Vac3 mower. A while ago, I noticed that
occasionally it wouldn't start when hot. Now, the problem is very
severe. When I start the engine the first time (when the engine is
cold), no problems. But the engine would run for only a couple of
minutes. Then, it'd quit. Once it quits, I can't start it again. I
need to wait for an hour before it'd start again. But once it
starts, it'd run for a couple of minutes and quit. And the waiting
game begins.

I changed the filter and the spark plug to no avail. I tried
running the engine with the gas tank cap off. No use. I cleaned
the carburetor. Nothing changed.

What could be the problem? Thanks.