Stihl 026 chainsaw - no power

[ejb]

Thanks everyone for all the suggestions. Glad to know this 026 can crank out for another 10 or more years...these saws aren't cheap.

Anyway, looks like the clogged muffler screen was the correct answer to the question; I already had fresh gas and a new spark plug, but didn't help at all. A good cleaning of the muffler and screen seem to do the trick...so thanks for that suggestion.

BTW: I used gasoline to clean it out (after removing from the saw)...is the a better/safer product to accomplish the same thing?

[RobertN]

A little Gunk parts cleaner(or similar product), and a toothbrush works. Then blow it out with compressed air.

Or, use diesel. Diesel has a much higher flash point than gas, so the chance of it igniting is much less.

Since I got my EMT certs while I was a volunteer Fire-fighter, I have always had a box of diposable latex gloves around. They are handy for that kind of work, so your hands are not in the icky stuff.

That excessive back pressure is a doozy; Diagnosis: Chainis sawous Constipationous [img]/forums/images/graemlins/grin.gif[/img]

[bczoom]

</font><font color="blue" class="small">( Anyway, looks like the clogged muffler screen was the correct answer to the question</font>

Glad to hear it was a cheap fix. Consider everything else you did to it either preventative maintenance or just a good tune up.

Brian

[Michael_E_Tx]

Just a suggestion: If your spark arrestor screen was plugged, it is also possible/probable that your exhaust port is carboned up as well. If you have the muffler off, check the port to see if it is it's original size, a restricted exhaust port will also really affect performance.

Mike

[SkyPup]

I tossed the muffler screen on mine decades ago.....screams allot better without it. [img]/forums/images/graemlins/wink.gif[/img]

[RobertN]

Be careful out there... It is not a muffler screen, it is a "spark arrester screen". Watch it in dry condidtions...

[FBBSBG]

I had a similar problem with my 1984 vintage Stihl 024. It started running fast then slow, almost like the gas tank was nearly empty with no power. In the past I've had to clean to exhaust screen and that helped, but not this time. I also cleaned the air filter, but it didn't help.

Since it was acting fuel starved, I took the fuel pump cover off and - low and behold - it had a lot of sawdust just under the cover. Looked like enough sawdust to keep the membrane from vibrating freely.

There is a small air hole on the cover that allows the air pressure to equalize, but I'm still puzzled how so much sawdust got under the cover. Could it be an air leak in the membrane that I could not see? Anyway, I didn't break the seal, just cleaned the sawdust out and it runs like new for now. Hope this helps anyone with a similar problem.

[williekioti]

I know this is an old thread, but since it was dragged to the surface......

A good method for cleaning a clogged spark arrestor screen instead of using volitile liquids; place screen in a pair of vice grips. Heat it up with a simple Propane torch till hot. Then brush off with a small steel or bronze wire brush. Let it cool, then re-install. Done.

FBBSBG, that membrane is your metering diaphram and yes it needs to be able to move freely with with changes in pressure. It opens/closes the needle valve allowing fresh fuel mix from the tank into the carb. With time and cutting with dull chains too often the fines can accumulate in there to restrict movement. Best advice? Keep your chain sharp so you're throwing bigger chips and blow out the airbox (not just the filter) once in a while. Good luck.

[D7E]

RobertN brings up an oft overlooked point -- chain saws need high octane gas. I have an 026 and the manual says 91 or higher. I'll bet only 1 in 100 users has ever read this or follows it.

We cut hundreds of cords a year and have always used cheaper or dyed farm gas in all brands of saws including ( 2x 026 and 2x ms260's) and most of which are many years old now with no problems .

[RobertN]

They'll run on regular.

I run premium, based on inputs from a friend who is and arborist. He figures these are 10,000+ rpm motors. They are like miniature race engines. So he runs hi grade gas and oil.

We cut hundreds of cords a year and have always used cheaper or dyed farm gas in all brands of saws including ( 2x 026 and 2x ms260's) and most of which are many years old now with no problems .