After 30 years, my chain saw quit..

As the title says, my 30 year old reliable chainsaw decided it needed a break. It's a Stihl 025, and doesn't seem to fire. I gave it a visual, nothing obvious, removed the spark plug, there was moisture on it, dried the plug and let it sit for about 15 minutes. Put it back together and still no good. I'm not the best at troubleshooting these things, but I don't mind working on them, once I know what the problem is. Any suggestions?

 

Thank you! That gives great direction to get this figured this out. I'll report back.

 

How long has it been sitting? What fuel was used? Has the carb ever been serviced?

 

It hasn't been sitting long, I've used it off and on throughout the winter, probably cut about 4 cords. I use 91 no ethanol, I also add fuel system cleaner. The carb has never been touched. I'm good at cleaning and maintaining it after a day of cutting. I'm just heading out to try what MasterMech suggested earlier, I'll start there and see where it takes me. I'm kind of leaning toward the coil being the problem, but at this point who knows. Appreciate the questions!

 

It could be flooded if the plug was wet. To clear the flood, choke off, hold throttle wide open and pull about 20 times

 

Yep, but it is much harder with modern saws because the exhaust is so closed up. I find ported saws to be much harder, if not "impossible" to flood compared to stock.
Just a muffler mod helps with flooding.

Probably no spark.

 

That's good to know, that's much faster than what I've been doing.

 

I removed the starter, I'm sure that's the first time it's ever been off. It was caked up with oil and sawdust, and I noticed the flywheel contact, appears to be rusty. After taking a few pics, I cleaned it up, scraped the gunk off and took my air compressor to it, I also cleaned the flywheel contact off with some fine steel wool. The coil gap checks good. Put it all back together and it started up and ran good. A little smokey at first, but that cleared.

I did not do the spark plug against the cooling fins test. Without removing the spark plug wire contact and boot, and pulling it back through the grommet, I don't think there's anywhere to do that test. It's in a very confined space.

No broken or pinched wires, they look secure. The ground on the switch is in place and only contacting when the switch is turned off.

Of course my concern is it happening in the field again. Should I still do the spark plug test? Should I have also checked the coil contacts, and maybe lightly cleaned it? Or maybe just go ahead and replace the coil?

Edit; Looking at this again, that rusty fly wheel contact is probably the problem.

 

Probably just flooded.

 

After I gave up on the saw yesterday, I ended up helping the landowner for over an hour, I tried it again before leaving and it still wouldn't start. Wouldn't it have cleared by that time?

 

stihl kicking When I have had to check for spark I have used a small jumper wire with alligator clips on it and clipped one end to the muffler and the other to the spark plug. It helps to keep your hands free and not get any shock.

 

Not necessarily...did you use the choke the second time?
If you tried it without choke (especially if throttle was held open too) then yes, I would have expected it to have started up an hour later.

 

Great idea, thanks, I'll have to try that.

 

I guess I can't say exactly what I did.... but my usual routine, especially after sitting more than 10 minutes, is to put the choke on, yank a few times till it sparks, then turn choke off, and then it almost always starts on the 2nd or 3rd pull, sometimes 4 or 5. I don't touch the throttle until it starts, and then it's to idle it down.

I remember flooding it when I was getting used to this saw, eventually figured out the routine above, and it's been solid. This is usually a very predictable saw.

 

A small correction to my last post, I have to press the throttle to choke it… but I doubt that matters.

 

Spark arrestor screen in the muffler getting plugged up?

 

You mean you squeeze the throttle when you set the choke?
That is just setting the fast idle...not the same as pulling it over with choke off and throttle held wide open.

 

I’m pretty sure it’s clean, I had that apart at the beginning of the season.

 

Yes, I usually squeeze the throttle when setting the choke. I thought I had to do that…. I’m in my garage now, and I see what you’re saying. The choke can be set without squeezing the throttle. Another thing learned today.. just when I thought I had all that part figured out… Just a simple side comment turns into a learning moment.