Chainsaw winter adjustments?

Re: Chainsaw winter adjustments?

John K Jordan

Did you run it long enough to warm up?

Re: Chainsaw winter adjustments?

Keith Newton

Yes, I think so. I managed to get about half way through a 32" white oak log, but it was just short burst, then sluggishness. I was wondering if the H screw needed to be opened a little to make it run richer.

I made sure the filter was clean, and have looked to see if there are any damper gates for the air flow, but don't see any. I just bought new high octane non ethanol gas, and mixed synthetic Stihl oil. The closest station that keep non ethanol is a small neighborhood station. I'm wondering if they get a different formula gas for Summer and Winter, and if I got what was left over from Summer.

Re: Chainsaw winter adjustments?

Hugh

Have you cleaned the spark arrester screen on the exhaust ?

Hugh

Re: Chainsaw winter adjustments?

Jake Niedling

I had a similar problem just as you described. I finally took it in and they replaced the carburetor for about $80 or so. My problem is that I don't run it enough during the year and was using ethanol gas. New carburetor and problem gone. I would have thought that it could have been cleaned, but they don't do that. Lesson learned.

Re: Chainsaw winter adjustments? *LINK*

Clifton C

On my Stihl there is a plastic baffle that is switched for summer or winter use located under the shroud, just over the air filter. When positioned for winter use, warm air is redirected from around the cylinder, over and around the carb. A quick google of a 391 shows you might have this feature. Check out page 34 on the attached link. Clean filter, fresh gas and a spark is usually all you need, but I've replaced a lot of fuel lines that just crumble when you pinch them so that may be another area to check.


Winter Ops

Re: Chainsaw winter adjustments?

Keith T

Do you know how to set the high speed mixture? It may be more than that...The ethanol in the fuel will eat away the rubber fuel hose in the tank, and the tiny particles end up in the carburetor inlet screen. That happened to my Stihl saw.

Thanks Clifton, I'll bet that will do it

Keith Newton

I started with this manual, but was speed reading, and must have just blasted by it. I was trying to get some cut before dark, but didn't make it.

Re: Chainsaw winter adjustments?

John K Jordan

I don't do anything different for my saws in the winter (I have three Stihl gasoline powered). I use the Stihl oil (with stabilizer) mixed 50:1 (I think) with hi-test pure gasoline only.

I'm assuming you use the starting procedure in the manual or it might even be difficult to get started. Once started I feather the trigger until it runs clean then run it wide open for at least 10 seconds. (I aim it at a clean board or something and use the wide open opportunity to watch for chain oil splatter to make sure the lube pump is working.) My saws do seem to run better after I began using this wide-open warmup. Maybe it blows something out.

If I have trouble I clean or replace the spark plug and make sure the air filter is clean.

If the fuel filter is clogged it could be starved for fuel.

If the saw sits for a long time a thin layer of "varnish" can build up on things inside the carburetor. I've taken many carbs apart and cleaned and reused the old parts successfully but never tried that on a chainsaw. If it has ever had gas with ethanol in it some rubber and plastic parts may be damaged and new fuel line and carb might be in order. I was told replacement carbs were available for not much money.

I have adjusted the low and high air mixture screws but I can't give good instructions. I do know that some of the newer saws (at the time I bought my last one) had plastic adjustment screw limiters that keep the saw running too lean, apparently to meet emissions regulations - some tree guys I know disable this and I did too on my biggest saw. (If the mixture is too lean the engine can't reach full power and can run hot and wear out quicker.) It's been a while so I can't remember what I did to disable the limiter but it should be obvious. The big saw did run better after this and some adjustment.

JKJ

Often that is a small split in the fuel line

Dick Coers

The fuel line inside the tank can split with age. That split can get exposed to air as you tip the saw, then it sucks air. Replace the fuel line first and see if that helps. Plenty of videos on youtube with instructions if you care to do it yourself.

Re: Often that is a small split in the fuel line

Keith Newton

Thanks Dick, I'll check that. After changing the baffle, it did better, but I still couldn't run full throttle. After spending about an hour out there sawing and splitting, I was thinking, Who needs a fire? I don't need no stinking fire! I was needing to get out my coat. ha

Re: Often that is a small split in the fuel line

Nathan Murphey

Check the oil flow, if the chain is not getting oil it will bog down the saw and will not run at high speed.

Re: Often that is a small split in the fuel line

Mike Brazeau

You get warm three times cutting wood, - cutting, stacking and then burning. Only winter exercise better is cross country skiing.

Re: Often that is a small split in the fuel line

Jorge

Snow shoeing!

you can get really hot, even ice skating too if you keep at it, and of course sleding firewood out of the woods...

Love my winter sports!

Re: Often that is a small split in the fuel line

John K Jordan

My winter sports are hefting bales of hay, breaking ice in drinking water, and cleaning stalls that the animals are kept out of in good weather!

JKJ

Re: Often that is a small split in the fuel line

Ron Pemberton

That used to be my past time. Breaking ice, cleaning stalls and unloading feed sacks. As far as hay bales, used to be my favorite, all I have to do now is look at a hay bale and I'm in bed laying on a heating pad for a day or two. Advanced age is not for sissys.

Re: Chainsaw winter adjustments?

Dennis in Southern Oregon

Sounds like a fuel flow problem. Check for a blocked air vent to fuel tank. In a safe place in case there are fuel spills, remove the fuel tank cap and see if it runs normally.

Re: Chainsaw winter adjustments? Follow-up

Keith Newton

I thought I would share my findings. Everybody knew it was a fuel problem, and If I hadn't just filled it, I could have easily discovered the problem. When I finally emptied the tank, I could see that the fuel line had a twist about 1" back from the filter.

When I pulled the line out of the fill hole, I could also see a hole, and the line was flattened and sticky, so had to replace the fuel lines, since there are two parts.

Thanks to everyone for the help.

Re: Chainsaw winter adjustments? Follow-up

John K Jordan

Glad it's working.

I know you said you used pure gas but the problem with the fuel line is what I've seen when gasoline with ethanol was used. Could ethanol have been used at sometime in the past?

If not, perhaps a gas station was claiming pure gas when it was not. Apparently some stations cheat. I bought a test kit to show how much if any ethanol was in gas. The kit is nothing but a calibrated glass vial in which you add water and gas, shake it up, and watch for a band of mixed gas/water. You could used any little bottle if you just wanted to test and didn't care about the actual percentage.

JKJ

Re: Chainsaw winter adjustments? Follow-up

Keith Newton

I was thinking I had read about the ethanol eating the rubber before, so have been careful not to use it for boats, 4wheelers and other small engines. However Ive never tested it.

I wasn't aware of that simple test. I found a youtube that shows how it works, and may test the one Im suspicious of. I usually add the oil to the can before adding the gas, so wonder if the test still works after mixing?

Re: Chainsaw winter adjustments? Follow-up

Jorge

Here in Maine, we cannot buy gasoline without ethanol, except for airplanes, so we have been using an additive for many years. It works well. I am out of it, so cannot go read the bottle, it comes in red or blue, I use the blue and my Huskys start anytime of winter.

The old one is a 360 and the new one is a 450.

Of late the 450 starts, runs great for 10 minutes and dies does not re-start. Next day does same. I changed the oil, and replaced the gas knob but everything looks good. Any ideas?

Re: Chainsaw winter adjustments? Follow-up

John K Jordan

>>>I usually add the oil to the can before adding the gas, so wonder if the test still works after mixing?

Seems like it might work. I could test my mixture but I'm way "overbooked" for the next few weeks. Maybe stop and get a gallon and test that.

From what I understand, you won't see a problem from one tank of ethanol mix. Perhaps if an ethanol mix was left sitting in the tank six months it would be a problem, I don't know. I've seen this on engines I got from others or was repairing for others. Sometimes the hose in the tank would be a soft, gummy mess, probably from long-term ethanol mix use.

We can easily buy the pure gas in this area although it is more expensive. I always use it in my chainsaws, pumps, yard machines, log splitter, sawmill, 4-wheelers, and other small engines. For engines 2-stroke (and 4-stroke) engines that need gas/oil mix I always use a stabilizer as well but I don't use it in straight gasoline engines (although I probably should).

JKJ

Jorge, Check for bad coil symptoms

Keith Newton

I think I've read that on some saws the spark gets weak as the coil gets hot.

Re: Jorge, Check for bad coil symptoms

Jorge

Thank you Keith!

I would never thought of that

Re: Jorge, Check for bad coil symptoms

John K Jordan

Ha, not only "weak" but it can be dead! Until it cools.

One way you might test the coil if you can get to it - I used to debug overheating electronic components by spraying with freeze spray. If heat was a problem cooling the right part would make the circuit work again. If cooling down the coil makes it run again you maybe you won't have to buy a new one just to test.

(At least some freeze spray is highly flammable so I'd spray then let vapors dissipate before trying to restart.

I don't know where to by freeze spray for electronics these days without a search, but I notice some of the brake cleaner I use seems to come out of the can icy cold. Maybe check Amazon.

I know you can buy medical freeze spray but I imagine it might cost a pound of flesh.

JKJ