Dolmar 343

[Tdkclydes]

Hello , I picked up a Dolmar 343 to use as a parts saw for a 143 rebuild . The 343 was not supposed to have spark and needed an ign module . The saw has spark but will not start , I read that if the module is bad it can have spark but the timing would be wrong . Yes = No ?

Thanks Tom

 

[AVB]

I can answer in a general term here, yes the electronics in ignition coils can go bad. I had small Homelite saw a couple years ago that would idle but would backfire through the carb at anything above idle which it turned out to the coil. I also had Kawasaki mower engine that would afterfire (out of the exhaust) which would had been a coil if it was as all in one unit. The coil trigger and timing unit was bad. Nearly sat my pants on fire as I didn't expect such a big flame out of the muffler. Sounded like a shotgun going off.

 

[nmurph]

Spark is triggered by the pick ups passing the magnets and creating a current. I think you more likely have a weak coil that doesn't produce a hot enough spark to ignite the mix when it's under compression.

 

[makguy]

If the coil is producing a spark there are a couple of possibilities: the coil is weak, or the coil is good and the timing is off (due to a sheared flywheel or key, which allows the pickups to fire the coil when not at TDC.)
I would lean towards a weak coil (more common) but an easy way to check if the flywheel is right is to rotate the pickups to the coil, and check the position of the piston (should be at the top of the stroke)
Good luck!