Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: Cut4fun . on August 10, 2017, 07:27:29 pm

Title: Coil info new one
Post by: Cut4fun . on August 10, 2017, 07:27:29 pm
Learned something new from a ole timer in the small engine repair for around 46 years. Think he said he was in his 70's.   

Called me and wanted to know if I had a coil for a S25da. I just so happened to have one pulled I parted out.

He went on to tell me he has only seen this happen once in all his time and now it makes 2 times.

Saw will not shut off.  Switch good, wires ground etc all good. Something goes wrong in coil and wont allow it to shut off.
I had never heard of such.

I sent him a coil and he installed it and it now shuts off.  Coil was the problem.

Anyone else ever heard or seen this before. Coils locked in run and never shuts  off when you try everything in the book.

Stihl 042 he said about 20-25 years ago.
Title: Re: Coil info new one
Post by: Al Smith on August 13, 2017, 05:11:57 am
My 2100 husky had a non working coil which I replaced with a used one .That coil did the same thing ,wouldn't shut off .The fix was spicing a high voltage wire to the plug wire and shorting it out that way .
That style coil BTW is the under the flywheel type SEM also used on 056 Stihls and sells for around 200 bucks for a new one .The 50 dollar used coil was a cheaper option .
Title: Re: Coil info new one
Post by: deezlfan on August 13, 2017, 07:04:34 am
Most of the coils I'm familiar with shut off by grounding through the switch so it does seem any break in
that small little wire would result in that symptom. When I think about it, I'm surprised it doesn't happen
more often, given the conditions I usually find under the recoil housings of saws I'm asked to repair. .   
Title: Re: Coil info new one
Post by: Philbert on August 13, 2017, 11:42:17 am
I have a friend with an MS026 that won't shut off.  Claims that he has had it to the dealer multiple times; replaced the grounding spring (whatever you call that metal strip); and the Master Control Switch.  Just uses the choke. Been doing this for so many years that it is just his SOP.  I assume that the coil is the only thing left to replace that could affect this. Some type of short in the grounding wire?

Title: Re: Coil info new one
Post by: Cut4fun . on August 13, 2017, 01:48:48 pm
I have no clue what happens.

The ole timer told me no type of grounding would shut these 2 coils off that I mentioned in OP.

Just shared so others would know if it happens to them to try another known good coil.