i was given a craftsman 18" chainsaw. It runs excellent for about 10 minutes, then cuts out. Will not start afterwards, usually for an hour or so. sometimes it sputters and runs for a few seconds. It has spark after it dies, and it gets fuel as well. Air filter and carb are clean. The high and low jet adjustments are correct as far as I know. all ports are clean. Any pointers as to what to look for next??

kevin k., March 2008

mine does the same thing, apparently carb ajustment, and it has spline ends so a repair shop has to do it.

Charles, April 2008

Kevin K,

Have you done a compression check yet? What does it yield when the engine shuts down? 2-cycle units typically will be upwards of 90psi. If there is a compression release, you can expect it to be about 60psi. The release was introduced to reduce the amount of effort required to pull and start the engine.

Also, i'd like to expand on what David started. When troubleshooting, always work from a Known Point. Start with a NEW spark plug. The naked eye can't always see a crack in a spark plug. Do your spark test in a dark workshop for best contrast. The ignition coil is suspect as well. While a "spark test" is valid, be prepared to buy a NEW coil. Check the spark plug wire from the coil as well. Do a thorough check.

Good Luck

Paul, March 2008

Bad spark plug. It breaks down and the porcelen expands leaving the electrode exposed to jump inside the plug. Don't use NGK. Use Autolite or Champion.

David, March 2008

the first time i ran the saw and it did this, I checked for fuel in the tank. finding it full, I closed up the lid and tried it again... but still nothing. I will check the cap, but I am thinking it must be something else. Thanks for the suggestion,

kevin k., March 2008

It sounds like a fuel problem. An vacuum lock in the fuel tank? If you loosen then re-fit the fuel cap will it start again?

Most fuel caps have a small vent to prevent a vacuum building up but can get blocked.

Slartibartfast, March 2008