Lawm mower stalls

rile,

As gas is drawn from the gas tank air must come in through a valve, typically a cheap reed valve. These valves can fail. So you run the mower until a vacuum builds up in the gas tank and stops the flow of gas. Next time it stops take the gas cap off, put it back on, and try to start it. If it starts up then suspect the reed valve.

Dave M.

the only thing using a reed valve is a two stroke, and that would have nothing to do with building a vacuum in the tank.

Rile,

You've already done the test by taking the cap off. You have a bad valve or vent. Look at the cap, is it vented? Drain the tank, get a flashlight, and look for a valve. This is a really cheap fix, you owe me a cup of coffee.

Dave M.

Run with the gas cap loosened about 1/4 turn, see if that helps.

My couple thoughts were

• Bad motor oil, as strange as that sounds.
• Valve clearance problem, if it's an older motor
• Ignition coil going bad

If the engine is more than a few years old, it may have valve clearance problems. To check this isn't all that hard, with a socket set and a couple of feeler gages.

To fix it requires dissembling the engine, and not many people have the tools. I tried to make a living of small engine repairs, and I do have the tools.