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Discussion Starter · #1 ·
Hi everyone. I have a problem I hope you can give me some insight on. It's a FS81 Stihl Handel Bar trimmer. It has intermittent and weak to no spark. I would usually change the coil, but this one also has a small electronic device wired to the coil. It is connected with one wire inline from the coil to the kill switch. Is this the electronic ignition module that is built in to the coil on the ones I've seen without it? I tried somethings that may shed some light. The spark is too weak to just the spark plug gap but I can feel it when I use my fingers grounding to the cylinder. And if I disconnect the "module" the spark gets even weaker. I checked for continuity through the coil and compared it to a known good one and it failed, no continuity from secondary coil wire to ground. But that's comparing a coil with built in module, if that's what it is. That's really all I have. Thanks and I'll wait for some help.
 

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The little electronic device is a trigger, it is probably bad, you can replace it with a Rotary 9334 for about $20. I had the same problem with a Kawasaki 150v I could feel spark but it wouldn't run, the trigger was firing at the wrong time, the Kaw part was $75 however the Rotary part worked just fine. Have a good one. Geo
 

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Discussion Starter · #3 ·
hey

Hey Geo, thanks for the info. It's nice to know that the device is a trigger.
A friend gave me this Handlebar trimmer to sell for him and it was running good when I picked it up. So when I got it home and it wouldn't run I kind of panicked. Then I tore it down to make sure that the kill switch wire wasn't shorted out, it wasn't. But when I put it all back together it worked. Now it seems to be working, it has started every time. So my question now is do you think it was the trigger? Are they known for having an intermittent problem like this?
Thanks for the help
 

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Hey Geo, thanks for the info. It's nice to know that the device is a trigger.
A friend gave me this Handlebar trimmer to sell for him and it was running good when I picked it up. So when I got it home and it wouldn't run I kind of panicked. Then I tore it down to make sure that the kill switch wire wasn't shorted out, it wasn't. But when I put it all back together it worked. Now it seems to be working, it has started every time. So my question now is do you think it was the trigger? Are they known for having an intermittent problem like this?
Thanks for the help
I would say it wasn't the trigger unless it had a grounding issue. Have a good one. Geo
 

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I've had more than one instance where the unit would start and run fine until it warmed up(10-15 minutes use) then lose spark.I have'nt encountered this on a Stilh with what I call a two peice electronic ignition,only the older Husqvarna chain saws.I remember it always seemed to be the more expensive part,I think the coil.I'll check with my brother tommorow(he cut his teeth on old Homelites and Husqy's)and post back if that is'nt correct.
 
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