No Spark

[Charles Mobley]

Replace the coil on my ms 391 stihl chain saw. Set air gap to 10 thousands. Put in a new spark plug. Checked kill switch, not going to ground. Magnet clean and working good. Still no spark. What have I missed?

 

[PV Hiker]

Shear key slipped on flywheel?

 

[Charles Mobley]

It

Shear key slipped on flywheel?

It should still fire. But I'll check it out.

 

[Mad Professor]

Is coil new/used OEM or aftermarket? Pretty sure universal and many other Stihl coils should fit/work.

Part#, numbers on coil, picture?

 

[lone wolf]

Is coil new/used OEM or aftermarket? Pretty sure universal and many other Stihl coils should fit/work.

Part#, numbers on coil, picture?

I think you are on to something maybe !

 

[stihltech]

Make sure you have a ground from the coil to the cylinder laminations.

 

[Charles Mobley]

I think you are on to something maybe !

I used OEM coil.

 

[lone wolf]

I used OEM coil.

Did you check in the dark for spark and if you are positive there is none then
flywheels can act up, can you swap that with a used one? You disconnected the kill switch, right? Do the part numbers match on the coils?

 

[WoodmanSr]

I used OEM coil.

Charles, read whether this may apply. Coil PN vs Air Filter style. Version #1 or #2 compatible coil pn.
Reported no spark on ms391 or ms311. Possible incompatibility of early style using plastic cage nylon filter (doghouse) vs cylindrical pleated filter are version 2 models.

Research other links on ms311/ms391 no spark.

https://www.arboristsite.com/threads/keep-in-the-back-of-your-mind-on-a-ms311.373549/#post-8341041

 

[Charles Mobley]

Did you check in the dark for spark and if you are positive there is none then
flywheels can act up, can you swap that with a used one? You disconnected the kill switch, right? Do the part numbers match on the coils?

Yes indeed, I checked for spark in the dark and unplugged the kill switch. Cleaned the magnets on the flywheel.