OT - chain saw mix

Northvale PA · Jan 27, 2019

I have been using non-ethanol gas for my saw mixes, about 40:1 ratio. I have 2 Stihl 026 saws. One is about 25 years old, other 15. Newer one runs fine on the mix. Yesterday, the older one (which I had the gas line replaced 1 year ago) was running fine but started to stall out like it was sucking air. I poured the mix out and put in some of the pre-mixed 50:1 stuff I happen to have. Now, it ran continually but at about 15% less speed. No power, basically. So, I poured half that out and put in half my 40:1 mix and the thing ran like a champ. No sucking air symptoms and plenty of power and speed. But the pre-mix stuff is $20 per gallon. So, now what? Shoot for 45:1 and try that? How temperamental are these things?

Dave BN · Jan 27, 2019

Does your saw have an air vent to shut off cooling air flow in cold weather? My husky does. Also I use winter(lighter) bar oil in cold weather.

Dave in Michigan.

guido · Jan 27, 2019

Hello Northvale PA,

Sounds like your need to adjust the carburetor for the mix you want to use.Easier to adjust the carb, then trying a mix that works. Gas quality could also be an issue, if the can mix works fine @ 40/1,

Guido.

Billy NY · Jan 27, 2019

That does seem kind of odd, like an intermittent mechanical problem, tiny pin hole leak that conveniently did not act up when you were doing some trial and error diagnosing with the fuel types. I've always run my own carefully mixed fuel using stihl 2 cycle oil with good results, but recently started using moto mix, just to see how it runs on that, and when working on calm days, fumes are so much less noxious. No difference in power or performance best I can tell. I'll go back to ethanol free and stihl oil mix for production, run the other when I know it will sit.

Only time I had the kind of problem you describe is when the fuel line was compromised, problems were intermittent, runs fine, then not so fine with varying degrees of performance lacking in between. Since changing out that fuel line, runs like it should.

Donald in MN · Jan 27, 2019

stihl saws use an impulse hose from the crankcase to the carb. it pumps the fuel. i use to work at a place that sold stihl. we usually check and replace those hoses when there were problems. you said that the fuel hose was replaced was this hose checked ? also there is a hose from the carb to the engine sometimes the hose clamp at the engine comes loose and the hose slips or tears but this is rare. you can check both hoses by looking between the air cleaner housing and the clutch housing. using a pen light. these hoses would cause an air leak and cause the saw to run lean

Russ from MN · Jan 27, 2019

The difference between 40 and 50 to 1 should have very little effect on how the saw runs, it sounds like you have a varnish buildup in the fuel system. You can either adjust the high speed jet, or some Seafoam might fix it, but running lean like this is not good for it, can cause it to run hot.

coshoo · Jan 27, 2019

You may have repositioned the fuel pickup end in the tank when you turned it upside down to dump out half the fuel. Always make sure the fuel pickup is sitting nicely in the bottom of the tank before use.

Mutt and Jeff · Jan 27, 2019

I call witch hunt or witches brew.
So the ethanol dissolved the gunk the no ethanol made after years of use and storage
dislodging the micro goblettes and loosening the flow characteristics of the pumper action lever needle and seat.
Taking into considerations the micro screen in the 2nd section of the mid casting or the carb.

If it continues to baffle you take it in and have the fuel system serviced (filter and kit)

John in Md. · Jan 27, 2019

That micro screen probably is clogged with white dust and the diaphragms are probably getting stiff after all those years. Could use a good rebuild kit for carb and new hoses and tank filter.

OT - chain saw mix

Northvale PA

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Dave BN

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guido

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Billy NY

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Donald in MN

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Russ from MN

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coshoo

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Mutt and Jeff

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John in Md.

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