Lawn Mower Runs for about a Minute, then Shuts Down

Old 06-24-15, 11:52 AM
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Lawn Mower Runs for about a Minute, then Shuts Down

My son is trying to repair a neighbors mower, but having some issues figuring out what's wrong. He's pretty good with repairing/maintaining mowers, but having an issue figuring this one out. If a make and model helps, I can provide, but I figure most small engines are basically the same.

The mower starts up without issue, and runs smoothly for about 60-90 seconds, then shuts down. He has cleaned the carb, and replaced the thermostat. Filter and plug looks good. Any idea what else might be wrong?

Thank you
Old 06-24-15, 12:39 PM
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Knowing what specifically he's working on would help a lot. You said he replaced the thermostat. Is it a liquid cooled engine or is the thermostat on an auto choke mechanism?
Old 06-24-15, 12:51 PM
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I'd put an inline spark tester on it to see if ignition is cutting out. Does it have a low oil shutdown? I'd check that too. Does it restart right away? If not, how long do you have to wait? If it restarts quickly, I'd be thinking fuel obstruction...
Old 06-24-15, 01:01 PM
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I agree that more information would help. Meanwhile, starting at the easiest, I would check the fuel cap to make sure that is clean and that the vent is not obstructed. After that, did he disassemble and clean the carburetor, or simply spray something into it? The latter seldom gets to where it needs to be.
Old 06-24-15, 01:24 PM
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My guess would be fuel. For whatever reason the fuel is not flowing freely into the float bowl. You can try removing the air filter and when it starts to cut out give it a little squirt of carb cleaner down the throat. If it recovers momentarily, fuel starvation.
Old 06-24-15, 01:24 PM
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It's on an auto choke mechanism. I'll get more details if needed, but it's just a Craftsman 6.75 walk behind mower.
Old 06-24-15, 01:47 PM
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Please post the model number so we can see what engine it has. Have a good one. Geo
Old 06-24-15, 08:29 PM
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Reach the choke linkage and close it by hand when the engine starts to die. Does it keep running then?

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