mower runs for a couple of minutes only

What kind of ignition?

A cracked coil, allowing moisture into the coil would act this way.

When the coil heats, the cracks expands

What type ignition?

Thanks for the quick response. The mower has a Tecumseh OVRM120-22032E engine. I looked it up and found that it has a solid state ignition.

While the mower is on the "hot shut down" unscrew the spark plug, lay it on the frame, reconnect the wire. Put the whole thing in the shade so you can see, and yank the starter. Look for spark. If you get spark, think other than ignition. Please let us know what you find.

It's a long shot. But I've known of mowers that needed an oil change to behave similar. I like Castrol, which has worked well for me.

Could also be valve clearance problems.

It still has a coil. You need to take the plug out and see if ithas spark once you get it hot. Basically 98% of the problems wiht these small engines are fuel or ignition. Check for spark to eliminate or confirm the ignition.

Are you sure there is gas flow to the carb? A clog in the filter screen at the bottom of the tank (or in the hose) could cause this since eventually enough gas would get through to fill the float or diaphragm chamber of the carb so the engine starts and runs normally but quickly dies and won't restart. An hour later enough has seeped through to let it start again.

John Smith wrote the following:

You didn't mention checking the oil. Did you?

wierdly my mower with briggs engine has the exact same prolem and the local repair shop is flooded with broken mowers

When it wont start spray in some starting fluid, and remove the plug and check for spark. What you describe is what has happened to me several times and it was the ignition module, eventualy it wont start at all. it could also be the coil but starting fluid and checking for spark rule out ingition.

I would have thought the spark plug. You got 2 bad plugs and keep swapping them? I've seen it happen.

Cheap check. Does it run okay with the gas cap removed?

As the gas is consumed, more is required. If the gas cap does not have an adequent vent, the resulting vacuum prevents additional gas from being consumed.

Or it could be a malevolent foreign god.

Hmm. Spray some ether into the carb, then pull the plug and give er a big yank. I sense an ether explosion about to occur. Like the old limerick "and lightning shot....."

I'm nominating this one for an award. Spray ether into the carb, pull the plug, and yank the cord. This could be confused with a solar flare, or GI flame thrower, having burned down four or five houses. What a maroon.

Champion had a bunch of bad CJ-8, years ago. Try different brand.

Take a trip to the small engine repair shop. If you wait for an answer here above the noise of the constant bickering between know-it-allsm mowing season will be over.

Gas or Spark problem, I'd dribble a little gas into the throat of the carb and try to start it. If it starts and runs a little its a fuel problem, no start its a spark problem.

Jimmie

I checked it. No sparks. I think I can rule out carburetor and gas tank vent now. What next? Replacing the ignition module?

Yes. I'm sure there is gas going into the carburetor. When I removed the carburetor and disconnected the tube going from the gas tank to the carb, gas gushed out of the tube. And when the mower "hot stopped", I immediately removed the bottom screw from the carb bowl, gas ran out of the bowl.

Actually, I changed the oil along with air filter and spark plug.