# Troy Bilt trimmer ignition



## Bill from NJ (May 10, 2006)

I have a Troy bilt (MTD) string trimmer that has no spark:
There are only 4 parts. 
Ignition module, 
flywheel/magnets, 
spark plug, 
kill switch.

Removed kill switch
New plug
Took flywheel off, and can lift a large set of vice grips with the magnets (lots of magnetism)
Replaced ignition module with New module (twice) and no spark. Plug wire is integral part of module.

Is there a run of bad modules floating around?


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## hankster (Jan 1, 1998)

Normally there is not problem with new modules... two bad ones would be extremely rare so I would think the problem lies elsewhere. How are you checking for spark? About the only good way to check is with a "gap" type spark checker.... using a plug grounded on the engine will not always give you a good indication of spark even if there is. To make sure it isn't the wiring remove the one wire that plugs into the module when you are checking for spark.


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## Bill from NJ (May 10, 2006)

Could not see any spark in a darkened garage - new plug held against the block. Ultimately I put a screw in - in place of the spark plug held it in hand, and had my hand against the block. There was not enough juice to feel it. I also had the kill switch wire completely removed. Are the magnets in the flywheel two separate magnets, or a single horshoe magnet buried in the flywheel? If a single magnet, maybe it was cracked inside?


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## hankster (Jan 1, 1998)

It is two magnets. I would find it hard to believe you have had two bad modules. I've fixed 200+ MTD engines (which is what a Troy Bilt is) in the past 4 weeks and I haven't seen a bad module. In over a 1000 in the past couple years I have seen maybe 2 or 3 bad modules total. The gap should be .012" or about the width of a business card but that is not highly critical. I would still suggest using a spark tester.


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## Bill from NJ (May 10, 2006)

It is mind boggling - there is no spark.
I even hooked up my cordless drill to the shaft (spark plug out) and could not create a spark with it spinning quite fast.


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## Bill from NJ (May 10, 2006)

I just sanded all the contact surfaces and reduced the gap to about 010. It seems to have some spark on the bench turning it with a cordless drill.. Time to assemble it and add fuel.


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## Bill from NJ (May 10, 2006)

It looks like the coating from the manufacturer must have had some non-conductive ****. After the vendor said they would not accept returns on electrical parts, I figured emery paper was fair game. It is running fine now.


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## hankster (Jan 1, 1998)

Good you got it running. I suspect the gap was too large then. There is no electrical connection other then the kill switch so any coating shouldn't have an effect on the spark.

Funny this should be brought up. In the past 4 years I've been working on the B&S 4-cycle weedeater engines, I've never had to replace an ign. module.... had to replace two of them today.


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## Bill from NJ (May 10, 2006)

The original module had no coating at all on it. The replacement was covered with a black paint. I sanded the surface clean on both sides of the mounting holes, and reduced the gap from about 013 to 010. The screw holes are clearly the return path for the spark plug current. I am not sure which was key.


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## Bill from NJ (May 10, 2006)

Ran about 15 minutes and died. No spark again. Guess the module was intermittent. Bought a new different brand.


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## truenorth777 (Mar 28, 2006)

Another thing to make sure is that the ground from the electronic ignition isn't touching the block. 

Check and be sure that the ground wire isnt bare in one place that it is grounding out which would cause no spark, hard starting and not to start at all. (it is the small usually black wire)

Hope this will help.


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