Head scratcher!!

[trooney]

At least it is for me. First time its happened. Got an 034 off this site that was mostly complete and decided to fix her up. Had some problems along the way, stihl evedently changed some parts slightly while retaining the same part no. Got her together, started her up but she'd quit after start up. Put a new fuel line in her, the vent was good, impulse line looked good, so I figured seals or base gasket. Shes old so seals wont hurt. Put new seals in and she did the same thing. This time she was torn down to the bare neccesities and I noticed she was sparking along the spark plug lead where it goes through the case under the recoil. It was causing it to short out. Took the coil out and looked at the spark plug lead and it looked fine, no visible cracks anywhere. Put another coil in and she ran fine. What would cause a spark plug lead to ground out if there are no visible cracks?

 

[Agrarian]

Cable manufacturing defect? Invisible crack?

 

[misterhandyman]

Electricity takes the path of least resistance. Maybe the insulation was worn thin or compromised at that spot. I have seen it lots on vehicles where the spark plug wires just have a bad spot and the spark leaks out

 

[GMB74]

The cable insulation can break down over time.
Or microscopic cracks develop.
Can't see these things, but add some moisture and watch the fireworks!

 

[trooney]

It even had that sheath over top of it, for lack of a better description. Dont know. I flexed it, looked real close and I could not see anywhere it was compromised. Really weird!

 

[Manxman]

The internal core could be damaged which wouldn't show externally. A new HT lead would be my best guess at this juncture.

 

[pbillyi69]

i have an old 046 that is very low hours because when it rains that saw shocks the piss out of ya. it has done it since it was new. it went back to the dealer several times and they couldnt figure out why. i have been holding on to it to try and figure out why for 20 years. i have always assumed it was a bad wire or possibly the coil. it is a very strong running saw but totally useless for production if you cant run it in the rain. edit: it is a good rainy day project... lol

 

[av8or3]

Take a saw out in the dark sometime if you suspect ignition trouble. I’ve seen it run from under the cap down the glass insulator to ground on the hex. Anyway, the trouble will “jump” out at you. lol.

 

[stretch5881]

Crazy stuff happens. I worked on an old Homelite saw that would run perfect....until you set it down. Put it on the ground and it would kill instantly.
I was testing out a power broom by sweeping the granite out of the lawn. Every time I was under a power line, it would kill.
You were lucky, you saw the spark.