Push mower keeps stopping

Jbanister98

Jbanister98

Forum Newbie
Hi, I have a MTD 21" self-propelled 139cc OHV push mower. It runs strong for 10 minutes or so then stops. If I wait 15-30 minutes I can usually get the last 10 minutes of mowing done. I have such a small yard and this is really frustrating. I have replaced the spark plug, changed the oil, air filter, fuel filter and fuel line. I've also pulled out the carburetor and it looks clean. I'm imagining that it's overheating but I don't know what else to do to help with that. Any suggestions would be appreciated.
 
Next time it happens loosen the gas cap. If the engine regains it’s power your cap is bad. You the engine stops remove the cap and then reinstall. If you can restart right away and cut for another 10 minutes, again cap is bad.
 
Do what rivets said, but if no luck, I would suspect a faulty ignition coil failing when it heats up.
When it dies, does it sputter and spit, or just like you flipped a switch and it's off?
 
Rivets said:
Next time it happens loosen the gas cap. If the engine regains it’s power your cap is bad. You the engine stops remove the cap and then reinstall. If you can restart right away and cut for another 10 minutes, again cap is bad.
Click to expand...
Thank you I will try this on my next mowing attempt.
 
Okay, so new gas cap didn't change anything. Mowed for 10 minutes then sputtered and died. Is the ignition coil my last option?
 
It sure sounds like it, especially since you said you have to wait about 15 minutes to cool down...
That's what I would do..
Another option is to buy an inline spark tester and check for spark after it dies...
 
I give up, ignition coil installed and it only want 8 minutes. If it needs a valve adjustment I'll have to take it on somewhere and after that money and all the parts I've put into it I might as well just get a new one. I'll sell this one to someone that knows how to fix it or wants it for parts. So frustrating. Thank you all for your suggestions.
 
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