Stihl MS181 ignition coil

[spandit]

disconnect the two wires and try it, have you got the insulator in place?

 

Yes, the plastic spacer is there. I had the black wire disconnected and can try it without the yellow wire too. I'm cranking it with a drill, anti-clockwise (which is the way the recoil starter turns it). Will try again but don't hold out much hope.

[spandit]

Still no joy. Put the coil and plug from an MS211 in and it still wouldn't start. Tried my spark plug in the other saw and it wouldn't go. Will change my plug but still don't reckon it would work. Baffling.

[GardenKit]

Not sure if this will help you.

 

According to a Stihl service bulletin issued in 2013, the coil was changed from 1139 400 1307 to 1139 400 1311 in 2013.

The bulletin states that they are not interchangeable .

 

The difference in appearance is that the earthing terminal on 1307 is bent at an angle whilst the 1311 is straight.

 

Each coil uses a different loom.

[bmp01]

I dont understand this either. The only other component to change is the flywheel. But quite how that could go bad i have no idea.

[spandit]

Magnets seem good in the flywheel. I'd have thought putting the coil pack and plug from the MS211 would give me a spark but doesn't seem to.

[bmp01]

Magnets seem good in the flywheel. I'd have thought putting the coil pack and plug from the MS211 would give me a spark but doesn't seem to.

 

It's a good method of fault diagnosis - swapping in known good parts - and there ant that many parts in the ignition system so yes should have worked.

Leaves you with limited number of reasons why it's not working -

- remainIng unchanged parts at fault, flywheel, wiring etc

- you've installed the known good parts incorrectly, possibility of a short?

- Known good parts have gone bad in the transition or been broken during assy.

- known good parts not compatible, alignment issue with / without spacer?

I'm grasping at straws...

 

You could try the reverse, put the old parts on the 211, one at a time, might help to narrow down the suspects.

 

Is the 181 barrel a genuine one by way?

Edited May 31, 2017 by bmp01
clarification "with / without spacer" added

[spandit]

One thing I hadn't tried for some reason is the spark plug from my working chainsaw. £4 later and I have 2 working saws

 

Replacement plug is exactly the same as the old one and I can't see any obvious faults. Ho hum. Bit chilly to be out there anyway

[bmp01]

That's a bit of a shame not to get to that sooner but nevertheless a good result. 

 

I've had the same issue with these small plugs, insulation cracked, arcing happened inside the plug,  not across the electrodes. Never seen a bad std sized plug. I've posted about this before,  can't remember when so I'll add the picture again here. 

 

Edit: the black lines across the ceramic are the arcing lines. ..

Edited March 1, 2018 by bmp01
See edit note in text

[peatff]

It's always the first thing I check when a saw starts to get hard to start because it's the cheapest option and the easiest fix.

[Guest]

Hi, rebuilding stihl ms181 chainsaw and also have problem getting a spark. Have new plug and changed the ignition coil ( a cheap one) with no success, my question is, can the magneto fail or is the problem likely to be the coil?