Stihl Electronic Ignition - Gets Stuck In Full Advance?

[SteveSr]

Hello,

I have noticed an issue with my vintage 1993 034 Super when starting it. It will either start easily or try to rip the fingers off your hand or your hand off your wrist!

This morning it was probably in the upper 30s or low 40s during the first cold start. It pulled over so hard that I thought that it might be hydro locked. I don't remember this happening before. So I pulled the plug out and it was dry. Put everything back together and finally got it to start.

I was working at a local county charity firewood cutting workday so had a lot of warm starts and restarts. Sometimes it seemed that the spark advance was stuck on. Every pull would try to yank your fingers off. Last time I turned the switch off to make sure that it wasn't my arm and pulled it over without problems. Next pull I flipped the switch on and it started up easy with one pull without trying to pull my hand off.

So have any of you ever noticed this behavior on any of the early Still electronic ignitions?

 

[Old2stroke]

That sounds like the kind of gremlin that can show up in electronic circuits, annoying intermittent faults that can't be chased down until full failure. The electronics don't actually do the advance, the coil is positioned relative to the FW and piston TDC to give max advance (just like old points magnetos) and what the electronic package does is ****** the ignition from this max setting to give easier starting without recoil kickback, so when the electronics starts to go funny, it's possible that the ****** function could be the first to go and the ignition would go back to an advance of close to 30 deg BTDC. Electronic systems are great until they fail and there is no good way to predict the lifetime of a semiconductor. You DON'T want to know how dependent your car is on electronic systems, only good thing is the auto manufactures have spent more money and use many mil spec semiconductors, be nice if chainsaws were treated the same way.