Things You'll Need
Spark plug wrench
Spark plug gap tool
The Stihl 180 is a homeowner-grade chainsaw, offering light weight and strong cutting performance in a compact package. Though all Stihl saws are designed to provide years of trouble-free service, if your saw is running poorly or won't start, there are three things to check: Is the saw getting fuel? Does the saw have spark? And is the saw getting air?
Check the obvious things first. Make sure the saw's fuel tank is filled with fresh fuel that has been mixed in a 50-to-1 gas to 2-stroke oil ratio. Ensure that the stop switch is set to the start position if the saw is cold or the "Run" position if the saw is warm.
Remove the cylinder cover by turning the black knob on the back of the saw 90 degrees counterclockwise and then lift the cover to disengage it from the pawls at the front of the saw. Remove the air filter and blow off any wood chips with the compressed air. If the filter is soaked with oil or fuel, it can be washed with dish soap and water. It must be completely dry before it is replaced on the saw.
Remove the spark plug boot by twisting counterclockwise while pulling back and up. Remove the spark plug using the spark plug wrench. Inspect it--if it is sooty or oily, clean with a wire brush. After cleaning, inspect the insulator for any cracks or chips, and replace if necessary. Before replacing the plug, use the spark plug gap tool to set the gap to between .025 and .030 inch. Screw the plug back into the cylinder by hand and then tighten with the spark plug wrench. Replace the spark plug boot, making sure it snaps firmly into place.
Try to start the saw. If you are only getting fuel and spark, turn it off and replace the air filter and attempt to start again. If the chainsaw starts, you are good to go. If it's still not starting, the saw may have more serious fuel delivery, electrical or compression problems and should be evaluated by a qualified professional for small engines.
Always operate the chainsaw outdoors or in a well-ventilated area.
Always wear appropriate eye and ear protection when operating a chainsaw.