Jonsered Chainsaws

[A_sharp]

920 no spark. - I'm hoping this is the correct place to post this question. In a previous thread I got help identiying an internal case air leak but before dissasembling the 920 I wanted to see what other issues there are with the saw and discovered no spark. A little strange as I managed to get this saw running when I first got it 15 years ago. I discovered an air leak back then, got busy and left it on the shelf until now. Here is what I have done to troubleshoot the ignition.

Disconnected the grounding switch
Checked spring and connection to spark plug
New spark plug
Checked wiring connections between flywheel device and coil
Flywheel air gap is .011", magnet seems very strong
Resistance across coil 1.055 kOhms
Resistance across flywheel device 77 ohms (not sure what this is called)
Made sure spark plug was grounded and after many starter pulls no spark.
Purchased a cheap inline spark tester which did not show any spark either. Tried this unit on my ms290 and it lit right up.

Any other tests or things I should try?
There are after market ignitions available but they do not look identical what is in the saw now. Has anyone used these and/or would you recommend one to purchase?

As always thanks for helping a rookie!!
Harry

 

[Real1shepherd]

Did you trace the wires back to the module to ensure none were bare or touching each other? Common ill in the soy insulation of the 900 series J'reds.
Unusual that you had fire 15 years ago, sat on a shelf, and now no fire. If the module is supposed to be grounded to the case, super clean all that up. If it has insulators, then no.

Not sure what you're calling "flywheel device".... pics?


Kevin

 

[A_sharp]

Did you trace the wires back to the module to ensure none were bare or touching each other? Common ill in the soy insulation of the 900 series J'reds.
Unusual that you had fire 15 years ago, sat on a shelf, and now no fire. If the module is supposed to be grounded to the case, super clean all that up. If it has insulators, then no.

Not sure what you're calling "flywheel device".... pics?


Kevin

I did trace the wires before but on a closer look one of the spade terminals was only hanging on by a couple of strands. I will re-solder tomorrow and check ground connections for cleanliness, that I have not done.
Here is a pic of what I called the flywheel device. Is this the module and the coil is by the carb? Thanks

 

[Real1shepherd]

Yes, that's the pickup module(especially check those wires and connections!). The coil by the carb and close to the spark plug......sometimes called a coil module.

Inspect every mm of those wires from start to termination. There is an ability to swap ignition parts across all the 900's, albeit with some modifications. Spike 60 has probably done that out of necessity and the lack of available parts. Others on old AS threads have claimed to have done it.....

Kevin

 

[newwood]

So no spark: sounds like you’ve ruled out the on/off switch and the plug. I’ve had problems with the contact between the spark plug wire and the ignition module, so that’s the next thing I’d check (probably screws in). After removing the wire from the ignition module you can use a multimeter to check whether current or voltage is getting generated by the ignition module by touching the ignition module contact

920 no spark. - I'm hoping this is the correct place to post this question. In a previous thread I got help identiying an internal case air leak but before dissasembling the 920 I wanted to see what other issues there are with the saw and discovered no spark. A little strange as I managed to get this saw running when I first got it 15 years ago. I discovered an air leak back then, got busy and left it on the shelf until now. Here is what I have done to troubleshoot the ignition.

Disconnected the grounding switch
Checked spring and connection to spark plug
New spark plug
Checked wiring connections between flywheel device and coil
Flywheel air gap is .011", magnet seems very strong
Resistance across coil 1.055 kOhms
Resistance across flywheel device 77 ohms (not sure what this is called)
Made sure spark plug was grounded and after many starter pulls no spark.

Harry:
So no spark and you’ve ruled out a bunch of things including the grounding switch. I’ve had problems with the connection between the spark plug wire and the ignition module so I’d check that next (the wire probably screws into the module), and while the wire is off you can use the multimeter to verify that the ignition module is generating current when you pull the starter. Then I think the next suspect is the ignition module itself—easy to replace if you can find the right part.
Newwood

 

[Real1shepherd]

Noodling around in old posts for this saw model, the pickup module seems pretty robust if the wires are not bare/broken.....but a fair amount of trouble with the coils or 'coil module'. Newood's idea to double-check the coil's output and HT wire connection are sound.

If the HT wire unscrews, test continuity with it while bent in various positions.

Kevin

 

[newwood]

I did trace the wires before but on a closer look one of the spade terminals was only hanging on by a couple of strands. I will re-solder tomorrow and check ground connections for cleanliness, that I have not done.
Here is a pic of what I called the flywheel device. Is this the module and the coil is by the carb? Thanks

Maybe it’s just the angle of the photo, but that yellow wire looks like it’s transected