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.

 

[lone wolf]

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

Part numbers match?

 

[Charles Mobley]

Part numbers match?

Yes, bought from Stihl dealership.

 

[lone wolf]

Yes, bought from Stihl dealership.

Well double check everything, then It might be the flywheel.

 

[Charles Mobley]

Well double check everything, then It might be the flywheel.

That's the only thing I haven't checked. Got to make up a puller.

 

[lone wolf]

That's the only thing I haven't checked. Got to make up a puller.

Look them up on Ebay might be cheap.

 

[Charles Mobley]

Look them up on Ebay might be cheap.

Thanks.

 

[stihltech]

Back up to the part numbers. Were they looked up by serial number? So easy to get the wrong coil without a S/N.
Major difference is the air filter type (as previously stated) and fins on the top of the cylinder. And be aware that one coil may have been discontinued.

 

[BigChopper]

Thanks.

I just paid £6 for a stihl flywheel puller from ebay