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Push mower keeps stopping

#1

Jbanister98

Jbanister98

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.


#2

R

Rivets

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.


#3

Scrubcadet10

Scrubcadet10

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?


#4

Jbanister98

Jbanister98

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.


#5

Jbanister98

Jbanister98

Scrubcadet10 said:
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?
Click to expand...
It sputters for a few seconds then dies.


#6

Jbanister98

Jbanister98

Okay, so new gas cap didn't change anything. Mowed for 10 minutes then sputtered and died. Is the ignition coil my last option?


#7

Scrubcadet10

Scrubcadet10

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...


#8

Jbanister98

Jbanister98

Just got a new ignition coil today. I'll post after I install it and try again. Here's hoping it works.


#9

Fish

Fish

Sounds like it needs a valve adjustment.


#10

Jbanister98

Jbanister98

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.


#11

Mower King

Mower King

Jbanister98 said:
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.
Click to expand...
Sometimes, if the repair gets beyond the mowers worth or a repair you can't do yourself....it comes to that.


#12

Scrubcadet10

Scrubcadet10

Over Head valve push mower, valve adjustment should be pretty simple, plenty of videos on the interscreen, any good repair man that runs a business will/should know how to adjust valves....
I remember seeing the clearances for the MTD OHV engine.... i think it was .010" Intake and .015" exhaust... that is if my remembory is right ;)
Is it A MTD brand engine or a Briggs and stratton?


#13

S

slomo

Jbanister98 said:
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.
Click to expand...
Now you have two good spark plugs.

slomo


#14

S

slomo

Jbanister98 said:
It sputters for a few seconds then dies.
Click to expand...
Sounds like it is starving for fuel.

slomo


#15

S

slomo

Jbanister98 said:
Okay, so new gas cap didn't change anything. Mowed for 10 minutes then sputtered and died. Is the ignition coil my last option?
Click to expand...
Now you have two gas caps.

slomo


#16

S

slomo

Fish said:
Sounds like it needs a valve adjustment.
Click to expand...
Not from what I've seen in the past. Hard or no starting at all tells me valves. Running for several minutes, then sputtering, is not valves. Out of spec valve clearance should cause issues at all times. 8 minutes then it sputters, she is thirsty.

slomo


#17

S

slomo

Jbanister98 said:
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.
Click to expand...
So after all those parts that are new, clean the carb or buy another one. Did I say that?

slomo


#18

Fish

Fish

slomo said:
Not from what I've seen in the past. Hard or no starting at all tells me valves. Running for several minutes, then sputtering, is not valves. Out of spec valve clearance should cause issues at all times. 8 minutes then it sputters, she is thirsty.

slomo
Click to expand...
If the valves are too tight, it will start and run until gets warm, then the valves can no longer seal.


#19

Fish

Fish

Valve gap is too great, then the compression release will not function correctly.


#20

S

slomo

Fish said:
Valve gap is too great, then the compression release will not function correctly.
Click to expand...
This wasn't stated by the OP as an issue.

slomo


#21

S

slomo

Fish said:
If the valves are too tight, it will start and run until gets warm, then the valves can no longer seal.
Click to expand...
You make sense but it runs fine for a quoted 8 minutes then sputters.

Wouldn't doubt it could use a valve clearance adjustment. Just not for sure this is the main issue. You guys do more engine work than I by far.

slomo


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