Effect of temperature on chainsaw starting

FirewoodAl · March 01, 2018, 01:55:49 PM

I've been loving my new Stihl 180. It is the easy start model, and the dealer was kind enough to change out the new age chain tensioner for the old fashioned style that allows for smaller adjustments and a more positive locking after the adjustment. I love the fellowship of this forum, and the high level of brains possessed by the folks who comment here. Please take a look at my experiences in starting the 180 in fairly cold temperature with "mature" gas. I will appreciate your comments:

The saw had gas purchased on 9-2-17, zero ethanol, treated with gas stabilizer at time of purchase of gas. The ambient temperature was 34 degrees F, and the garage temperature where the saw is stored was 36 F. The saw coughed after the fifth pull and started up on the sixth. However, it would run at idle speed for about 3 to 5 seconds and then quit. If I gave it more gas during these periods, it would quit immediately. These start and quit episodes happened between 12 and 18 consecutive times. We theorized that the saw was quitting because it was cold.

I discovered that after more than a dozen idle and quit episodes the saw would idle a little longer if I rotated it to about a 2:00 o'clock position, with the pull cord handle and gas filler cap higher than if the saw were level. I kept the saw level from front to back, the bar and the engine housing were at the same height. I was able to maintain an idle in this position, so I let the saw idle for several minutes. After that it would accept more gas and come up to operating RPM. It stopped one more time when I began cutting wood, but performed fine after that. We were obviously working with old gas, but we believe that temperature of the saw was also a factor here.

Kwill · March 01, 2018, 02:25:20 PM

My ms250 stihl starts the same way whether its 80 or 20. I had trouble with it when I first got it and took it back to the dealer. They installed a new carburetor and haven't had any trouble since.

starmac · March 01, 2018, 03:43:44 PM

Seems odd, guys here keep their saws in the beds of their pickups and start them down to 20 below and even cooler, with no problems with them running.

My old logger friend that I pulled for just retired, but if he took one out of the bed of his pickup and pulled it over 4 or 5 times, no matter what the temp was, that saw was either getting some work done on it or going down the road.

Hilltop366 · March 01, 2018, 03:52:23 PM

Doubt if the temperature had any thing to do with it.

How long had it been since the saw had been started?

gspren · March 01, 2018, 06:48:59 PM

34F should have little to no effect on your saw. When I was younger my saws seemed to run fine down to 0F and colder, now in my 60s they don't want to run much below 20F.

limbwood · March 01, 2018, 07:21:46 PM

if it was tuned when it was warm out it could make a difference, the colder it gets the richer you have to set them, you could try opening up the low screw a 1/4 turn and see if it helps.

Hilltop366 · March 02, 2018, 08:02:27 AM

I'm thinking what limb wood said + if it has been sitting around for a while a bit of dried up gas in the jet(s) that got cleaned out as it ran more.

moodnacreek · March 02, 2018, 08:32:01 AM

Have a 170 that that only runs half throttle half the time [leans out]. Fill it up, turn it upside down, cuss at it and it might start and run perfect until next time.

ButchC · March 02, 2018, 08:37:33 AM

Without being there your experience sounds pretty typical for todays fuels, and a EPA saw set the way most are sold. I would first take it back to the dealer. Part of your purchase price is warranty work and if you dont use it goes into Stihls pocket. He should be able to improve it but he cant do what we can do at home which is richen it up past EPA regs.

Tinking with the carburetor can get a novice in trouble but backing the H screw out to the stop should help (if it isnt all ready there) and if it has an adjustable carb.

Whats happening in a cold crankcase is the fuel tends to settle out, then the saw leans out and begins to die, you blip the throttle and it first gets a gulp of air,, and dies. If you pay close attention to how it operates you will notice that the cold lean condition is followed by a fuel rich condition as it warms and runs as it should. This is the cold fuel that settled in the crankcase getting warmed up and into the cylinder. I have never owned a 180 but some saws are worse about this than others. I have a 370 Echo that is REAL bad about it. The leaner the carb is set to meet EPA regs also worsens the deal.

One work around is to let it remain on high idle longer before you un set it or even hold the throttle open to maintain fuel flow to the cylinder. Hi test fuel seems to help also.

John Mc · March 02, 2018, 08:07:20 PM

Quote from: FirewoodAl on March 01, 2018, 01:55:49 PMThe saw had gas purchased on 9-2-17, zero ethanol, treated with gas stabilizer at time of purchase of gas.

You are using 6 month old gas in your chainsaw? Even with a stabilizer, I won't do that. Run that stiff through your lawnmower or snowblower, or in the tank of your car (mixed with a tankful of better gas).

Canadiana · March 03, 2018, 01:44:48 AM

Sounds carby to me but old fuel is a possible issue as stated already. Fuel breaks down faster at warm temperatures or condenses water quickly when the fuel is cold and the rate of temperature change rises quickly. The more empty the fuel tank, (or jerry can) the more water can condense due to air capacity. The best way to keep members contributing accurately is to keep commenting. Yawn... time for bed...

petefrom bearswamp · March 03, 2018, 09:16:29 AM

I have not had problems with some pretty ancient ethanol gas in both my 40 yr old Homelite, 3 Huskies and my current Echo.
All have the lean problem in the winter, but will start OK if I hold my mouth right and turn the air blue.

Al_Smith · March 03, 2018, 09:13:07 PM

You probably have more problems at 90 degrees than you will at zero .Over heat one in hot weather it might take a while before it will start again .--been there .

FirewoodAl · March 04, 2018, 06:31:55 PM

Thanks for all these good ideas. The saw had not been used for seven weeks when it performed as I have described. I have made a resolution to start it up and run it at least once a month whether I cut anything or not. So what follows is the result of my saw temperature experiment:

The saw still had old gas, purchased on 9-2-17, no ethanol, stabilizer added at time of purchase of gas. We had begun keeping the saw in the basement because we theorized that the previous difficult starting might have been related to the cold 34F temperature of the saw. This time, the saw's temperature was approximately 60F. The saw coughed on the fourth pull, and started up fine on the fifth pull. There was no rough idle, and the saw performed faultlessly. This argues well for storing the saw in the basement during the winter months.

This Stihl saw gets much better fuel economy than my previous chain saws, which is why I still had gas from 9-2-17. However, it makes a lot of sense to put that older gas into my car, where it will mingle with a much greater amount of fresh gas, and get it used up. Then buy new gas for the saw!

starmac · March 04, 2018, 07:30:35 PM

I have read multiple times where pro loggers fallers hat use there saws are getting pretty adamant about only mixing enough gas for one day at a time, starting with fresh gas every morning.

I do know nearly every boat and small engine mechanic claims that over 90% of their business is gas related, but it has been that way before we ever had ethanol.
We do not have ethanol gas here, but I tend to think it does compound any gas problems where they do have it, just something we are going to live with.
So far I have not had problems, but what I have started doing with the one saw I carry in my log truck, which may get started 10 times al winter or just as likely not started at all, is filling the tank with the dealers canned gas. I don't carry gas on the truck, so this has worked well for me so far. It is too expensive to use in everyday saws that see much use at all, but a can of it last me 2 or 3 years in that saw.
That saw stays in the box on the truck and gets put in the shop nightly, the shop stays around 60 degrees, but we work down to 20 below or a little better that it sees during the day, so far so good.

John Mc · March 05, 2018, 07:31:50 AM

Quote from: starmac on March 04, 2018, 07:30:35 PMI have read multiple times where pro loggers fallers hat use there saws are getting pretty adamant about only mixing enough gas for one day at a time, starting with fresh gas every morning.

Wow! that seems excessive to me. I don't think I've ever run into someone who insists on only mixing a days for of gas at a time. Most of the heavy users (including pros) I know mix up a 2.5 gallon batch. Lighter users mix up a gallon at a time - and throw it in their car or lawn mower if it gets old before its used up.

weimedog · March 05, 2018, 10:12:38 AM

Having days here this year where there have been literally temperature drops from the low 40's to single digits, I've become more of a fan of the Autotune's from any brand! with the conventional carb's those who like to keep the saws running really crisp, temperature changes beget carb adjustments. To many a compromise is acceptable..tuning for winter, running really rich in the summer until a plug fouls...

BUT tune crisp in the 80 degree summer, and not touching that saw until a 1 degree day can cause a little heart burn. Air density / carb settings is the key. Colder air is more dense. Any one fly out of Colorado's Denver Airport in the summer and have the airline delay, even limit weight on the really hot days?

As far as fuel life, there is a point of diminishing returns. After a couple of weeks mine ends up in one of the old gas powered farm tractors (not diesel). Some of the two stroke oils have a "Stabilizer" on board to help. Alcohol isn't the end of the world but left too long likes to separate a bit or worse attract water. And thats before you consider the alcohol's effect on SOME brands rubber parts over time. Fuel lines/ carb diaphragms etc. So I use the stuff available that claims to be alcohol free. Put a little in the truck to "clear" the pump & lines, then fill the can. I have a fellow at work who every spring....I mean EVERY year for the last few complains that the saw is in catastrophic failure. Dumping the gas from the saw into a glass jar....those little clear "worms" running around the bottom of said jar tells the story...so I ask...fresh gas?? "Oh yea, I only use fresh gas! He says...

Go out to his truck and the SAME steel can that has been there since the last time is still the one used for "saw gas". Probably sat in that very spot all winter..

Al_Smith · March 05, 2018, 06:20:01 PM

I usually keep it about a month then dump it in an old Ferguson tractor that would probably run on kerosene if it were started first .It's not too picky what I feed it .
This winter I haven't cut much .Partly because it didn't get that cold and partly because I have no one to stoke the fire while I'm at work .If my lady friend is having an extended visit I fire up the stove .She kind of likes it . Another reason is the older I get the less enthusiastic I am about cold weather .There was I time I had to bear the elements to make a living but that time has passed.