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PK., Small Engine Technician
Category: Small Engine
Satisfied Customers: 1052
Experience:  Retired Owner of a full service shop and national parts sales website.
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I have a Craftsman 18 40cc Chainsaw about two years old.

Resolved Question:

I have a Craftsman 18" 40cc Chainsaw about two years old. It starts fine when cold but once warmed up, and it stalls or I shut it off, it will not re-start until I let it cool all the way back down to "cold start". once running I have to keep the trigger squeezed until I'm done as, it will stall once I release the trigger. I have tried to adjust the Idle speed screw, and, of course, the mixture is set at the factory. I have changed the sparkplug and air cleaner with no results, fuel is fine. I have noticed when removeing the cover to check sparkplug, that a sharp edge on the cover has worn through the Plug wire insulation and you can see the white silicone under the black insulation...but it is not worn all the way through. I was thinking of ordering a new ignition module to replace the plug wire.
Submitted: 8 years ago.
Category: Small Engine
Expert:  PK. replied 8 years ago.

I think you may be running too lean because of a stopped up carburetor. The plug wire, you can tape up with electrical tape, this is pretty common on some of these saws.


The part number for the carburetor isNNN-NN-NNNNand is available from any Poulan dealer. I have it listed at about $22 and that's about average. Poulan makes this saw for Sears. You can use any of the part numbers from Sears and save a little money by buying from a Poulan dealer.


I don't bother rebuilding these carburetors as for the price, it just doesn't make any sense. You'll spend about the same on a carb kit and cleaner as a new carburetor with none of the fuss of rebuilding.


It's very, very important to not run lean in a chainsaw. The carburetors are already adjusted lean from the factory to meet EPA standards so leaning out a little more will result in too little oil reaching the engine and in overheating.


Your symptoms could also indicate a vacuum leak from the carburetor seal or even a crank seal. But without the proper tools and block-off plates, you can't check these things. I would feel pretty comfortable in replacing the carburetor myself.


Let me know if you have any questions. Thanks, PK.


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Customer: replied 8 years ago.
I was leaning towards the carburator too. just wasn't sure once I saw the worn wire. Have not dissassembled it far enough yet to check for a possible loose screw on the carburator mount. Do you have a website so I can order a carb from you?
Customer: replied 8 years ago.
I "googled" your shop name as listed in your info and found the website and placed order. I felt you took the time to provide answer that sounds like a good probability, I may as well buy the part from you. Thanks