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Nobadays
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# Posted: 13 Aug 2021 07:34pm
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We started getting wood early this spring, it had warmed up a bit and was in the 70's mid morning. Saws did well early then started vapor locking. My older Echo CS330T and my wife's brand new M170 Stihl.... and her old Homelite. We were at our wit's end so after a couple of loads, each with an hour or more in there fighting saws...after they cooled some they would kind of run but die a lot. If you took the fuel lid off with fuel in the tank, you got a face full of gas! We kind of gave up. I ordered a new carb for mine, then after a part of a day cutting dead stuff around the cabin... same thing!
Frustrated I took it to a small engine repair shop and when I picked it up he said nothing was wrong other than old gas and a little adjustment. Well the gas was freshly mixed, 91 octane,
ethanol free with Stabil in it... he said it smelled weird.
Of course I'm scouring the internet with the symptoms and got on one forum where a saw mechanic answered a post of someone describing my symptoms, he said, "Winter gas, nuff said." Others agreed. So then I went down that road... what is the difference in summer and winter gas... to simplify, way more butane in winter gas so it vaporizes at a lower temperature. Found a post by the USFS with a warning to their saw operators about spewing gas when opening 5he tank in warm weather if winter gas is being used. Another tell tale was our gas jug even sitting in the shade looked like a basket ball... all swelled up!
Hmmmm.... I had bought that 91 octane in late November for my snowmobile. So, dumped the mix into my old Tracker tank.... emptied the chainsaws, then mixed a new batch of fuel with regular 10% ethanol fuel. Saws ran like champs... no vapor lock issues at all!
I learned something! Hope this helps any of you Northern habitating folks who also have winter and summer fuels in your areas!
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Brettny
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# Posted: 14 Aug 2021 08:22am
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I run into vapor locking a bit with any gas if I dont top off the tank on my ms460. My leaf blower, both weed whackers, 2 other chain saws dont care. I think the tank vent on my ms460 is a bit clogged.
I believe the newer saws now have cat converters in them. That could cause a whole other slew of issues. Also a ms170 is a prety base model saw that's really not built to be ran all day.
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paulz
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# Posted: 14 Aug 2021 09:09am
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Good tip on the summer winter fuel change.
I haven't pulled a chainsaw cord since I got my lithium saw...
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Nobadays
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# Posted: 14 Aug 2021 09:38am
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Quoting: Brettny ms170 is a prety base model saw that's really not built to be ran all day.
But it's light.... my wife mainly limbs and occasionally cuts rounds here at the cabin as I split. We are mid 60's, we don't cut wood all day anymore! Usually only about 3 hours and we have a pickup load and call it good!
I read... and noted on my saws, that the only vents on these small engines since sometime in the 70's? Is to allow air IN... no vents to allow fuel vapors to escape. Pollution thing.
Quoting: paulz since I got my lithium saw...
I broke down and bought a Makita top handle lithium saw... I like it as a saw but 2 x 18v/5ah will only last ~30 minutes of continuous cutting. I have 6 battery packs so can get 1 1/2 hours of cutting. Used it to fall one tree when I blew a chain off my Echo but mostly limbed with it. My wife used it more than I did after she flooded her saw... she just can't give that cord a good enough pull sometimes.
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paulz
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# Posted: 14 Aug 2021 10:03am - Edited by: paulz
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Yeah I haven't done any serious bucking with the lithium saw yet. I've been clearing my hillside for defensible space, mostly 2-4" cuts with a few larger ones. Sure is great for that, and limbing.
We have one more day of free green waste dumping, then I'll start bucking the firewood.
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Brettny
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# Posted: 14 Aug 2021 11:37am
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Quoting: Nobadays I read... and noted on my saws, that the only vents on these small engines since sometime in the 70's? Is to allow air IN... no vents to allow fuel vapors to escape. Pollution thing
If no vent than how would air get in to replace the removed fuel? They all have a vent. Google ms170 fuel vent. It looks like a rubber duck bill thing.
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ICC
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# Posted: 14 Aug 2021 01:29pm
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Quoting: Brettny If no vent than how would air get in to replace the removed fuel? They all have a vent.
one-way vent??
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ICC
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# Posted: 14 Aug 2021 01:47pm - Edited by: ICC
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I have not yet used a gas chain saw this year. But I have used and absolutely love my Stihl MSA 220 C-B. A friend has an EGO cordless that seems to work very well too for less money.
To be fair I should mention I have a family member who runs the local Stihl shop and I got a family price on mine. But I love the way it works as much as any saw I have used
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Nobadays
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# Posted: 14 Aug 2021 10:25pm
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Yes, one way....I DIDN'T say NO VENT... as stated in my post....Quoting: Nobadays the only vents on these small engines since sometime in the 70's? Is to allow air IN...
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RiverCabin
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# Posted: 18 Aug 2021 01:14pm
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Quoting: Brettny Also a ms170 is a prety base model saw that's really not built to be ran all day
That is correct but it is a pretty handy saw.
I bought one new and immediately switched to a 14" bar. The 16" bar is too much for it. The shorter bar makes it a great limbing saw.
The downfall of these saws is the carb. I got a second saw for free from a buddy who was moving. He had mixed up his gas with ethanol gas and had let it sit over the winter. Of course it wouldn't run come spring. Instead of fooling around and trying to clean it, I bought a new carb off Amazon for about $13. It ran like a champ until my Father decided I didn't need two of them and took that one home with him.
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Aklogcabin
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# Posted: 23 Aug 2021 12:09pm
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Your saws are make to run all day long . It's just an internal combustion engine that's smaller. If you're keeping it somewhat clean of old saw dust, I like to use air blower. I suspect you're oil pre mix is 50:1 are you mixing it too lean ?
What leads you to believe that it is vapor locking ?
If you're saws are getting older the fuel lines can deteriorate giving you running issues. Or get hard . You can trim the ends of the fuel line or better to replace if you can.
The fuel pumps are fairly simple devise that can have issues.
But since all 3 saws quit near the same time it appears like a common issue. So oil to gas mixture comes to mind.
Good luck.
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Nobadays
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# Posted: 23 Aug 2021 12:31pm
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AK… nope 50:1 mixture. The gas tank pressurizing, as a n unscrew the cap and get a face full of gas. Gas can sitting in the shade looked like a basketball from air pressure built up in it. Weed eater manual pump ball just air. Once the saws cooled all the way back off they would start and run. Many factors but research shows it was way Bree fuel vaporizing and it pressurizing the fuel system. Once I switched to standard fuel the app problems went away.
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