Stihl saws are reliable and last many years if properly cared for. Throughout the life of your Stihl, you will encounter many small repairs that can be fixed easily and cheaply with a few tools and a little knowledge. Stihl saws are two-cycle engines, meaning they only require three basic things to start: fuel, spark and air compression. By checking these three areas, you can troubleshoot the repairs quickly by isolating them from the other engine components.
Empty the gas tank. Use the toothbrush, rag and a little saw gas to clean out the tank.
Pull up the fuel filter resting at the bottom of the gas tank, using the pliers. Pull this filter off and replace with a new filter.
Disconnect the fuel line from the carburettor and pull out the fuel line from the gas tank with the pliers. Replace the fuel line as well. Reinstall the new fuel line and filter.
Attempt to start the saw. If the saw starts but dies when throttled or while idling, adjust the carburettor screws to increase the fuel/air mixture in the engine.
Pull the rubber plug connector off the spark plug. Use the sparkplug wrench to take out the sparkplug.
Scrape and clean the sparkplug, using the toothbrush, saw gas and rag. Pay careful attention to the sparkplug's gap and make sure it is completely free of gas and dirt by wiping it down with the rag.
Push the sparkplug back into its rubber connector. Let the sparkplug and connector hang about 1/4 inch away from a metal spot on the engine housing.
Pull on the starter cord gently and check the gap between the two metal points for a spark. If there's no spark, replace the sparkplug and test again.
Inspect the starter wires to make sure they are connected and not damaged.
Set the saw on the ground. Put your right foot on the throttle's handle. Pull up on the starter cord. The saw has compression if the engine makes a whirring or chugging noise.
Remove the starter cover if the saw doesn't have compression. Replace the starter cord if it's broken or damaged. Clean the fan, cover and starter area with a toothbrush, gas and rag.
Remove the air filter cover by unscrewing the black knob just above the throttle. Unscrew the air filter and clean the filter and cover with toothbrush, gas and rag. Replace the air filter if it's damaged or extremely dirty.
Take off the muffler's cover, using the Allen wrench. Pull out the spark-arresting screen from the muffler. Clean that as well with gas, toothbrush and rag. Replace if chipped or damaged.
Many saw problems are related to the carburettor. Saws stored with old fuel still in the carburettor will often not run properly. Fuel lines and fuel filters are cheap and often solve many gas-related problems.
Take the saw to a certified Stihl mechanic if in doubt about performing any of these tests.