Chainsaw problems....

Director

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Thought I'd get some expert advice before I take it in to the shop. I've got a Makita DSC-6401 chainsaw which is about 18 months old and has been working fine. Starts every time and just goes like a champ. Was using it about a month ago and ran out of fuel, I'd finished the job I was doing so I didn't bother to refuel at the time. This morning I mixed up a new batch of 2-stroke, this model uses 50/1 ratio so going by the instructions on the oil bottle it was 20ml of oil per litre of petrol. So far so good.

Now here's the funny bit, the saw started up OK and will idle just fine, it seemed to work as normal for a few minutes then it just died. Restarted OK and idles just fine but whenever I hit the throttle it just stalls like it's starving for fuel? The fuel filter looks OK and I can't any cracked lines, the problem occurs with the air filter removed and also with the fuel cap off (in case the vent was blocked). So the only thing I can think of is that I stuffed up the fuel mix in some way but it's pretty straight-forward so now I'm stumped?

So chaps, any ideas?
 

Ken W.

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You got the fuel/oil ratio correct. How fresh was the fuel you used? Was it or the previous fuel you used ethanol based? That's a couple of questions to start with. Apart from that it could be, although a month is not usually long enough to cause problems, that there was a little residual fuel from the last use which has gummed up the carby. Another possibility is condensation which can also clog jets. If you've got some carby cleaner , mix a thimble full in the tank and let it idle for a while or if you can, spray some down the carby. It may be enough to dissolve the blockage. Another consideration is that with the cooler conditions it may just need a tune-up.
 
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Director

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Thanks Ken, no the fuel I used is only a couple of weeks old, the same fuel that Use for the mower (but mixed up 50/1). I refuse to use ethanol based fuels for anything pretty sure it's unleaded 95. I don't have any carby cleaner but it IS quite cold here ATM (as in 12c)? I'll leave it a week or so until the weather warms up but if still no good might just take it in to the shop. They can give it a tune and sharpen the blade for me as well. :)
 

Mark

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Great advice there Ken that was very interesting!

I had a similar problem a few days ago with my Stihl chainsaw it would kick over but press the trigger it died... I mixed up a new batch of fuel, drained the tank, and after several pulls (like about 20) it kicked over and ran like new. The thing is, my original fuel mix was not very old - maybe a month!

Perhaps condensation is a factor particularly during winter. .. I remember as a tanker driver (petrol) it wasn't abnormal to sometimes drain 3 or 4 litres of water out of the tanks on a winters morning.
 

Director

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That's what I don't get though. I made the batch up yesterday morning and the tank on the chainsaw was already empty from the last time? I'll wait till the weather warms up and try it again I guess. :)
 

Ken W.

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Here's a few more thoughts I've had ...
  • Is the chain free to run? - as in - is the chain brake on or clogged up with debris?
  • Give the adj screws a turn and carefully return back to where they were - this may dislodge any gunk.
  • Check that the muffler isn't clogged. Wasps or other bugs may have taken up residence for the winter - mud wasps are creators of much frustration year round.
    • Test the filter by removing it (i'm assuming it is in the tank) and submerge the fuel line. Start and run the saw. If it runs as it should then the filter is your problem and needs replacing. If the problem continues then put the filter back on.
 
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stevo

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Just charge the battery :p

I used to have an old Suzuki 4x4, they always had carby issues. We used to swap the spark plug leads over to make them backfire to clear the carby and off you'd go. But yeah it was usually the jets that became clogged with dirt. Going offroad usually meant that the fuel tank was being shaken around and any dirt in the bottom could get sent through the lines.

So I'd probably first spray a heap of Carby Cleaner in the carby (as Ken mentioned), and if that didn't work I'd see how difficult it is to remove the jets from the carby and clean them out.

If the zombies come you'll be in trouble!
 
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