Chainsaws won’t work in the heat

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serenitytree

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intermountain west
I have a collection of chainsaws that seem to all stop working when the weather turns hot. Yesterday we had a 261, electronic carb , 400 electronic carb, 500i, 201 conventional carb, and a 192 conventional carb on site. We used them from 7 AM to about 1230 with no problems, all getting gas from the same gas can. They all seemed to work fine. About 1230 or customer showed up to load logs into the trailers, this was part of the bid. When he rolled up all the chainsaws stopped working. couldn’t get any to start. Or if they did, they would fire and die immediately. Thinking maybe it was a gas problem I sent a guy to go get fresh gas. While he was gone, the 261 fired up and worked, when he got back and we put fresh gas in, all the saws except the 261 worked intermittently, the 261 was just down. This kind of thing has happened to me from time to time over the past two years (how long I have been in business) when the weather gets over 80°, it was 90 or so yesterday. I do know about the summer/winter tab and have them all set to summer. I tried fresh gas- but why would they all work fine from the gas can all morning then when it gets hot the gas suddenly doesn’t work? Air filters are cleaned, probably not as often as they should be- but I cleaned one of the air filters just in case that was the problem. I ran a tuning cycle on the 261 twice and the 400 once, but that did not solve the problem. Most of the time I run 91 ethanol free, sometimes I run 91 regular “up to 10 percent ethanol” when I am not close enough to one of the very few places that sell 91 clear around here. I’m pretty sure yesterday’s fuel had ethanol, but have had it happen with 91 clear. I really don’t understand why things like this happen.

Maybe the gas can sucks in cool wet air at night due to a pressure leak- fresh gas should have solved that- but the 261 would not run on fresh gas and the 400 quit a few times. Letting them sit for a while and try again in 20 minutes sometimes they would run fine.

It’s not the air filters all plugging up at exactly the same time.

It’s not the winter summer tab.

I live in northern Utah and work around salt lake/Utah valleys. We have dry heat. Elevation about 5000. Most of my saws are electronic adjustable so the weather shouldn’t be a problem.

After loading one trailer with logs the skid steer (not mine) also started having problems. The engine would rev higher than it should on its own. No trouble codes. So I have kind of concluded that while traveling in Africa I angered a which doctor and was cursed. I feel like I have a very unusually high frequency of equipment failure in general, but this chainsaw thing is really bugging me. Why would they all stop working when it hit about 80-85?
 
all of my saws used to do that, turns out it was fuel issues, crack the fuel cap and close it again, if that seems to help, try a pre-mixed fuel (they aren't gas) and see if that helps, I run VP 50:1 in all my saws now, its stupid expensive ($30 a gallon) but so far has been worth it

maybe a different mix oil would help, red armor or amsoil? stihl oil is pretty crap

ethanol only really matters if the fuel dries up, I don't bother with getting ethanol free unless im getting 15 or 20 gallons at once

is the skidsteer gas or diesel?
 
I have a collection of chainsaws that seem to all stop working when the weather turns hot. Yesterday we had a 261, electronic carb , 400 electronic carb, 500i, 201 conventional carb, and a 192 conventional carb on site. We used them from 7 AM to about 1230 with no problems, all getting gas from the same gas can. They all seemed to work fine. About 1230 or customer showed up to load logs into the trailers, this was part of the bid. When he rolled up all the chainsaws stopped working. couldn’t get any to start. Or if they did, they would fire and die immediately. Thinking maybe it was a gas problem I sent a guy to go get fresh gas. While he was gone, the 261 fired up and worked, when he got back and we put fresh gas in, all the saws except the 261 worked intermittently, the 261 was just down. This kind of thing has happened to me from time to time over the past two years (how long I have been in business) when the weather gets over 80°, it was 90 or so yesterday. I do know about the summer/winter tab and have them all set to summer. I tried fresh gas- but why would they all work fine from the gas can all morning then when it gets hot the gas suddenly doesn’t work? Air filters are cleaned, probably not as often as they should be- but I cleaned one of the air filters just in case that was the problem. I ran a tuning cycle on the 261 twice and the 400 once, but that did not solve the problem. Most of the time I run 91 ethanol free, sometimes I run 91 regular “up to 10 percent ethanol” when I am not close enough to one of the very few places that sell 91 clear around here. I’m pretty sure yesterday’s fuel had ethanol, but have had it happen with 91 clear. I really don’t understand why things like this happen.

Maybe the gas can sucks in cool wet air at night due to a pressure leak- fresh gas should have solved that- but the 261 would not run on fresh gas and the 400 quit a few times. Letting them sit for a while and try again in 20 minutes sometimes they would run fine.

It’s not the air filters all plugging up at exactly the same time.

It’s not the winter summer tab.

I live in northern Utah and work around salt lake/Utah valleys. We have dry heat. Elevation about 5000. Most of my saws are electronic adjustable so the weather shouldn’t be a problem.

After loading one trailer with logs the skid steer (not mine) also started having problems. The engine would rev higher than it should on its own. No trouble codes. So I have kind of concluded that while traveling in Africa I angered a which doctor and was cursed. I feel like I have a very unusually high frequency of equipment failure in general, but this chainsaw thing is really bugging me. Why would they all stop working when it hit about 80-85?
Try opening the gas cap and tighten again. It releases the pressure from the tank during the hot weather. It works for me when I use my STIHL leaf blower and trimmer.
 
Another vote for vapor lock, however fresh fuel should have solved that issue, assuming it wasn't still some sort of winter blend. (And from a different fuel station.) If the saws fire back up after cooling off and run normally till they get heat soaked it's a probable issue.
 
Had a local drop off a Stihl 290 with the same complaint, would not start when it was hot. Fuel system pass pressure test, carburetor passed pressure test, fuel tank vent was working, then I noticed the prefilter/summer/winter shutter was missing...

I had a parts saw in the attic and he was back in business.

Mark
 
Another vote for boiling fuel; I've run into the same issue, south Cariboo in BC at 3500-4000' elevation. Gasoline is not what it used to be, I think a chainsaw-using refinery chemical engineer would have the technical answer, but boiling point seems to have gone down. Not an issue in modern cars due to the pressures at which the fuel system runs--I guess.
 
Another vote for boiling fuel; I've run into the same issue, south Cariboo in BC at 3500-4000' elevation. Gasoline is not what it used to be, I think a chainsaw-using refinery chemical engineer would have the technical answer, but boiling point seems to have gone down. Not an issue in modern cars due to the pressures at which the fuel system runs--I guess.
Carbed engines have more trouble with this.
 
Another vote for boiling fuel; I've run into the same issue, south Cariboo in BC at 3500-4000' elevation. Gasoline is not what it used to be, I think a chainsaw-using refinery chemical engineer would have the technical answer, but boiling point seems to have gone down. Not an issue in modern cars due to the pressures at which the fuel system runs--I guess.
Keep in mind that the fuel tank on a car / truck is remotely located, away from engine heat whereas with a saw, the fuel tank is right next to the heat source, the engine and vehicles use more fuel whereas a chainsaw uses little so the fuel heats up and boils and vapor locks.
 
Not an issue here, both my tractors are turbo charged air to air diesels with twin saddle tanks. Diesel, even ULSD off road diesel don't boil like gasoline does. No boiling issue with canned gas at all (Echo Red Armor) 50-1.
 
If I used my saws daily, canned fuel might be an expense issue but I don't so I use it. Nice thing about canned fuel is shelf life is 2 years opened and 5 years sealed in a full can. Unlike pump gas I have no issues, even in my Stihl FS66 brush cutter that sits idle 90% of the time. Starts right up, second pull always. I keep a couple sealed cans of Red Armor on the shelf at all times. I hear VP is good as well but no one sells it around here,
 
I have also had problems with saws or weedeaters left in the sun on a hot day. They all stay in the shade until needed. The California winter blend will boil at 90 degrees.
 
I live in Loveland, CO @ 5000’ and I have this problem all the time with my Stihl 261Cs saws on warm days (80 degrees +). Replacing the coils with the latest generation pn seems to help.
Hate to start the Stihl/Husky war but my 550XPs are still useable. The Huskys will struggle and frequently won’t idle but you can always get them restarted using the Hot Start procedure. Stihl needs to figure that out.
 
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