# Yard Man YM400 won't start?



## dpoc (Apr 17, 2006)

Hello,

I have a Yard Man YM400 31cc string trimmer that won't start. I was using it one day and stopped in the middle of trimming the lawn and when i went to try and restart it to finish the trimming i wouldn't start. I checked for spark and it has spark. Not sure it the gap is set right for the magneto or exactly what the gap is suppose to be. It also has compression. I even went as far as to dump some gas down the spark plug hole but no luck with that either.
Any suggestions would be appreciated...

thanks,
d


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## bugman (Aug 12, 2004)

How much compression, was it tested with a compression tester? It COULD have sheared the flywheel key, this would throw it off timing.


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## repair_guy (May 9, 2004)

With respect to bugman's reply,
unless you have a solid drive shaft with no clutch,I think that a sheared flywheel key is out of the question.Sounds to me like your spark plug is going to be shorted out,the on/off switch is bad,the ground wire is shorting against the cylinder or shaft somewhere or the trimmer is not producing enough spark.


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## hankster (Jan 1, 1998)

First change the plug and see if that helps. That uses a Ryobi style engine. I would pull off the muffler and have a look at the piston to see if it is scored. Next, pull the carb and look in the manifold hole... you should see a silver metal piece covering the hole.... if you happen to see the end of the crankshaft your reed is broken.


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