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Thread: Why won't saws start when hot?!

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    TreeHouser Nutball's Avatar
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    Default Why won't saws start when hot?!

    This seems to be a pretty common issue at least in my experience. I used to rarely if ever run chainsaws in the hot summer because it is too hot to work. I do it more now and of course know others that do obviously because we all need work. Recently my echo 271t which would always start in two if not just one pull when warmed up now takes 5-10 pulls. Is it vapor lock, fuel nearly boiling in the lines or fizzing out when it enters the carb causing a lean mixture? For the first few pulls it doesn't fire at all, then sometimes it does that thing where you hit full throttle and it wants to die. I'll go to check to see if it ran out of gas to have the gas boil out all over. A guy I work with will give me a saw to fix complaining it doesn't run right and is hard to start. I usually have no trouble with it, and run it till it's hot without issues, give it back, and he says it runs great for 20min then doesn't start.

    Do you guys who work in hot locations have this much trouble with starting hot saws? What is the solution? Do you know of any chainsaw models that tend to have this problem more than others, or is it pretty much with any? The only thing that comes to mind is trying 100% gas 93 octane, and add a little diesel to hopefully increase the boiling point.

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    TreeHouser Sponsor woodworkingboy's Avatar
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    Saws that stop running or won't start when hot can be an ignition coil going bad. When hot and not starting you might pull the plug to check to see if you are getting a spark.
    Bright days and dark days are both expressions of the great mystery. ~ Oglala Sioux

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    Treehouser Sponsor Skwerl2's Avatar
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    Yes, it's vapor lock. Been dealing with it for 35 years here in central Florida. You can do a couple things to minimize the issue, mostly just being aware that it is an issue and avoiding triggering it.

    First, I seem to have less issues with it when I use premium gas for my mix. It's 50 cents a gallon more than regular and if you burn 5 gallons of mix per week it's $2.50 per week. Most people use a hell of a lot less than that.

    Next, avoid leaving your saws or gas in the sun. I have closed boxes on my truck. If you don't, keep your saws in the shade somewhere.

    If your saw vapor locks, open the gas cap to relieve the pressure and then fill it up with cooler gas out of the gas can. If the saw has a primer then pump it until the primer ball is full of gas instead of air. When you start it you may need to play with the choke while hitting the throttle until you can suck enough gas into the engine to run right.
    -Brian

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    More biners!!! Sponsor pantheraba's Avatar
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    Good description of how to handle that...thanks. I thought I was getting that same problem today on a job. On a whim I checked the air filter (on my MS 290) and it was pretty cruddy. Cleaned it but still would not run more than a few seconds.

    I adjusted the L and H screws...ran them all the way in then back the proper amount. Saw started running perfectly. Maybe trash in a jet? Whatever it was that fixed the problem.
    Gary

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    TreeHouser Nutball's Avatar
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    Just what I want to hear, your 35 years of confirmation on this issue. You'd think that would be the first problem/solution in the trouble shoot list in the front of the manual to educate everyone, but we are all too smart to read a chainsaw manual because we might read something we already know.

    I had a 015 I used to use, the metal crank case with heatsink fin internal design (structural supports) in the gas tank quickly boiled it. That thing never stayed tuned right, but on the bright side it had a continuously adjustable choke allowing you to always "tune" it just right on the fly.

    I wonder if auto tune has vapor lock issues, probably does.

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    Mac Daddy Sponsor Al Smith's Avatar
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    Another thing that might help is to give them a little cool down period before you shut them down .I've seldom had a problem with a hot start with a Stihl,McCullochs yes in hot weather .
    You can hold the throttle open and drop start which would be easy on an 015 ,not so easy on an 066 .Do that one on the ground .

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    TreeHouser Nutball's Avatar
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    Thing about the 015 is you can tune it lean, so you can now create over lean all the way to over rich conditions using the choke for whatever the conditions. If I have to do a full throttle start on a big one, I used to jam my foot in the handle and use big toe to press the trigger, but boots don't fit.

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    Mac Daddy Sponsor Al Smith's Avatar
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    Big toe,you gotta be kidding .

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    I'm Not Slash Chris E's Avatar
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    so you can't drop (hot) start a big saw, neither can I

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