Chainsaw: Won't start
The 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 . If the fuel is fresh, 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).
These repairs may help solve your Chainsaw problem:
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.