# Stihl FS 80 Trimmer--No Spark



## Captgerryf (Jan 28, 2010)

Looking for suggestions on what to check on my Stihl FS80 trimmer to track down why it has no spark.

The trimmer crapped out at the end of last season, so I started this year by completely cleaning the carb. It had become increasingly hard to start and finally wouldn't start at all. I get fuel to the plug as it is wet after cranking, but don't seem to have any spark. Even tried a new plug with no luck. Holding the end of the plug to the block doesn't show any spark jumping the electrode gap.

Any chance I have a loose wire in the kill switch that is causing the system to ground out? Any other places I should check for a wiring issue?

Any suggestions would be appreciated as this has been a great trimmer and I would hate to have to go buy another one for want of a simple fix.

Thanks


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## glenjudy (Aug 26, 2006)

Captgerryf said:


> Any chance I have a loose wire in the kill switch that is causing the system to ground out? Any other places I should check for a wiring issue?
> .
> 
> Thanks


That's the 1st place I'd look. Also, coil may have gone bad.


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## billsmowers (Mar 21, 2008)

Disconect The Kill Wire If You Then Have Spark Then The Wire Is The Problem If Stll No Spark Then The Coil Is The Problem

Bill


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## rotti1968 (Apr 26, 2009)

billsmowers said:


> Disconnect The Kill Wire If You Then Have Spark Then The Wire Is The Problem If Still No Spark Then The Coil Is The Problem
> 
> Bill


Ditto, also just so you are aware depending on the age of the unit if the coil has gone south it may still be under warranty as long as its a registered unit.


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## Captgerryf (Jan 28, 2010)

*Location of Kill Wire*

Couldn't get to the trimmer after your replies as I had to do a million other things this past weekend, but I hope to get to it one evening before the grass really starts to pop here in MD.

Where does the kill switch wire attach near the engine? 

I would rather not take the handle mechanism apart if at all possible and if I can just disconnect the kill wire near the engine to isolate this as a cause, that would be preferable.

Thanks again for the replies.


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## rotti1968 (Apr 26, 2009)

if you remove the top cover of the engine you will see the coil and there should be besides the ignition lead 2 wires connected to the coil. unplug the wires and test if you have spark its your kill circuit. if not its the coil....


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## Captgerryf (Jan 28, 2010)

*Still No Luck*

Got a few minutes to tear the trimmer apart and easily located the kill wire, but there was only one connected to the coil.

Disconnected that and still no spark.

Took the coil off and the part of the coil that sits above the flywheel had a ton of greasy debris on it so I figured that might be impeding the spark. Cleaned it, reinstalled with .010 gap (IS THAT CORRECT FOR THE GAP?) and still no spark.

If my gap is correct, then I guess I have a bad coil and maybe why it was hard to start toward the end of last year as the coil was slowly crapping out.

What's a ballpark estimate for a replacement coil for a FS 80?

Unless anybody has any more suggestions on what I can try, I'm off to the local Stihl dealer for a replacement coil unless it is cost prohibitive.

Thanks for the replies on this issue.


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## rotti1968 (Apr 26, 2009)

Captgerryf said:


> Got a few minutes to tear the trimmer apart and easily located the kill wire, but there was only one connected to the coil.
> 
> Disconnected that and still no spark.
> 
> ...


That coil is in the 37.00 price range. part number 4137 400 1350
and the air gap should be about the thickness of a business card


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## Captgerryf (Jan 28, 2010)

*Walbro Coil*

Pulled the coil off to take to my local Stihl dealer and found out it is manufactureed by Walbro and is a Type MB.

Does anybody know of a website where you can buy a Walbro Type MB coil?

I just want to see if the web price would be significantly better than the Stihl dealer price.

Actual part# painted on the coil is:

Stihl 4137 1307A followed by MB-17A 2707 (in the 2707 string of numbers, the first 7 and the 0 are worn pretty good, but I think they are the correct numbers)

Rotti1968--You indicated a part number of 4137 400 1350. Is that a new number for 4137 1307A?

Thanks again. I got to get this back together as the grass is growing here in MD!!!


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## rotti1968 (Apr 26, 2009)

That is the most recent number I have in my parts breakdown. One thing to keep in mind that when it comes to coils etc most of the time with Stihl they are proprietary.


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## Captgerryf (Jan 28, 2010)

*Up and Running*

Got a new coil from the local Stihl dealer last night ($38) and installed it on my FS 80. Fired up on the first pull!!!

Thanks for the replies/help on getting this resolved. 

Now I'm ready to beat back the grass for the next seven months here in MD. Supposed to be near 80 degrees here today and that is no April Fools Day joke!!!

Rotti1968--Your part number was correct. It apparently is a repalcement part for several coils as the directions included show it replacing a variety of different part numbers including the one I had listed.


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