Gas Chainsaw: Won't start
The chainsaw engine needs gas, compression and spark in order to start. First, make sure there's fresh gas in the tank-old gas accumulates water and burns poorly. Replace the fuel if it's old. Add fuel stabilizer to the gas when you refill the tank to help keep the fuel fresh.
If the fuel is fresh, check for and replace cracked fuel lines. Air enters the carburetor instead of fuel when the fuel lines have cracks. If the fuel lines are okay, you may need to rebuild or replace the carburetor because a dirty carburetor won't supply the engine with fuel.
Next, disconnect the spark plug wire and remove the spark plug. If you see deposits or corrosion on the electrodes, replace the spark plug.
Finally, to check for compression, remove the spark plug, press your thumb over the opening and pull the starter cord. If you don't feel air pushing from the cylinder, it's likely that the piston rings need to be replaced. (For an accurate compression reading, use a compression gauge.)
Rebuild the chainsaw carburetor
Rebuild kits are available for most carburetors. The kit contains essential components for rebuilding a carburetor, such as diaphragms, seals and gaskets. You can sometimes fix a fuel supply problem by dismantling and cleaning a carburetor. Use the kit to rebuild the carburetor after cleaning it.
Replace the chainsaw carburetor
The carburetor mixes air and gasoline in the proper proportions to create a combustible gas. If the engine starts and then sputters, or doesn't start at all due to lack of fuel, you might need to replace carburetor. It's often more cost effective and practical to replace the carburetor rather than rebuild it.
Replace the chainsaw fuel lines
Fuel lines become brittle over time and can crack or tear. Replace a fuel line that's brittle or damaged. Be careful to install new fuel lines on the engine the same way the original fuel lines were configured.
If your chainsaw isn't running well, a dirty carburetor could be the problem. You can take it apart, clean it and rebuild it, using a carburetor rebuild kit. This repair guide takes you through the process.
15 minutes or less
If the engine won't start even though there's fuel in the chainsaw, the carburetor could be the problem. Sometimes, it's easier to replace the carburetor than to clean it and rebuild it. Follow these steps to do the job yourself in about half an hour.
15 minutes or less
June 1, 2016
By Sears PartsDirect staff
Learn the basics of taking care of your chainsaw and solving common problems.