Craftsman 40cc 18in Bar Chainsaw


Old 02-10-09, 05:06 PM
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Join Date: Feb 2009
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Craftsman 40cc 18in Bar Chainsaw

hi...I own a craftsman 40cc 2cycle gas chain saw with 18in bar...not sure how old the saw is...maybe about 3 yrs...near the end of summer last year I was cutting up tree that fell in my yard...things were going well and before I finished what I wanted cut saw started to stall out on me...I would start again...and stall out again doing this a couple of more times...I replaced the chain thinking this would help...did help some but still having problems...I used a friends saw to finish the job...until now I am wishing to use my saw again...I am not able to start at all...thinking that other parts are now needing to be replaced...I replaced the spark plug...replaced the carburetor...replaced the purge bulb for primming...replaced the filter...replaced the fuel with fresh fuel 40:1...I can pull the start cord until my arm almost falls off and still not able to start my saw...yes I am getting spark from the park i'm thinking its not an electrical problem...yes I am getting fuel into the cylinder head...I am at a loss...can anyone help me...I would greatly appreciate this...thanks...
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Old 02-10-09, 06:51 PM
Join Date: Feb 2009
Location: USA
Posts: 323
If you fuel foul a plug, it's pretty much toast.

You can clean it up, but always have about 3 or 4 spare plugs just in case cuz it won't be the same again.

Before you try to start it, make sure the choke is fully closed. Once it pops, open the choke a little more then it should fire.

You said it was fresh gas, how fresh? I'm hoping no more than a month.

If you have spark, it should fire if the engine has air and fuel and compression...does it have good compression?

If you flood the motor while trying, save yourself the agony and replace the plug, it will drive ya batty

I would also install an Oregon 95VP chain/Microlite bar combo, would really wake up the saw.

Other than that all I can think of is a carb problem, could have been stalling out from being out of adjustment. If it stalls on the top end, open the high needle a tiny bit and see if it helps.

Also, when you use the saw ALWAYS full throttle, not half in case you were using it that way.

Carb doesn't have a real mix circuit for part throttle, idle or full.
Old 02-10-09, 08:19 PM
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Join Date: Jul 2001
Location: USA
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Wow, you're already into this a good bit now with all the new parts. I'm afraid it might be in vain though, as your description of the manner in which it failed, combined with the fact that it will not start with the parts you installed, makes me think the cylinder, piston, and ring(s) are shot. Remove the muffler and have a look inside the cylinder. Rotate the engine and look at the piston, inside the cylinder, and the rings. If there are scored spots and gouges, cut your losses, put it on ebay as a parts saw and pick up a new one. If the cylinder, rings, and piston look good, check the fuel lines for cracks or damage.

It's a common failure I've been seeing a lot of on modern 2-strokes. The EPA has manufacturers making their engines run so lean that there is little to no room for error, and the smallest carb restriction, air leak, or fault with the oil/fuel ratio can ruin the engine in minutes. Combine that with the cheap construction of a department store saw and the strain and heat these saws go through when cutting, it's a wonder they last as long as they do in my opinion.

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