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MTD Yard mach 17.5hp rider quits after 20 min


Gdad123's Avatar
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07-18-08, 01:17 PM   #1  
MTD Yard mach 17.5hp rider quits after 20 min

Hi- I have MTD Yard Mach mower with B&S engine.

31C707 0154 E1 04043ZA

It's about 5 years old. Recently, it starts and runs fine for about 15-20 min then it just dies. Wait about 30 min and it starts again. Seems to do this more under load when the blades are engaged. New Plug, fuel filter, carb is clean.

I was researching and found some saying the Magneto Armature ( thing that goes to the spark plug) is bad). Should I just replace it, or is there a way to test it under load?

From what I read, this seems to be a common problem with B&S rider engines.

Or- Am I barking up the wrong tree?

Thanks

 
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07-18-08, 02:01 PM   #2  
Your best bet it to check the spark immediately after it dies. No spark, then go after the coil. You do not need to trow money at the problem without checking for the correct problem. Good Luck.

 
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07-18-08, 02:17 PM   #3  
what's the best way to check the coil ( magneto armature as they call it)

the part is $50 shipped but to have a repair est that is $60 here just to look at it so I figure why not try the coil thing and see if that works.

 
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07-18-08, 02:21 PM   #4  
Twenty minutes sounds like enough time for a vacuum to form in the fuel tank because of a clogged vent hole. That starves the engine for fuel. Then the tank gradually gets back to normal, and it'll run again.

Under load and blades engaged = using more fuel, so the engine stops sooner.

Does it take several seconds of cranking to get it restarted? That's because the bowl on the carb is empty.

Try leaving the gas cap loose to see if that's it. Or remove the cap just after the engine quits to see if it hisses.

May be a long shot, but maybe not.

 
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07-18-08, 02:27 PM   #5  
Tried the loose gas cap, and then just replaced it. Same problem.

When it stops it seems to act like it's out of gas. I checked all the fuel lines, claen the carb, filters ( needed to anyway). Not sure at this point.
Does it take several seconds of cranking to get it restarted? That's because the bowl on the carb is empty.
When it dies after on it's very hard to start or turn over. You have to wait 10-15 min and then it will start again

 
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07-18-08, 03:08 PM   #6  
Hard to turn over after stopping when hot, but starts OK when it's cold. That sounds like the engine might be overheating.

Have you checked for clogged places around the shrouds on the engine?

 
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07-23-08, 02:28 PM   #7  
Repair Update- the new magneto armature part ( ref #333) fixed the mower. Common part for B&S engines. Not to bad to swap out. Mine was $47 with shipping and the prices can vary depending on who you get it from. Part for mine and other common are #492341

 
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07-23-08, 03:07 PM   #8  
That's great, and thanks for letting us know what it was.

 
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