How to Repair Stihl Saws

Stihl saws, like every kind of two-stroke engine, require three things to start and run: fuel, spark and air compression. If any of these three key components are missing or not functioning properly, you will have to repair the saw. But before you can start repairing broken parts, you must isolate the problem. Use these simple tests to make repairing the saw easier.

Things You'll Need

• Leather work gloves
• Diesel gasoline
• Old toothbrush
• Screwdriver
• Spark plug wrench
• Starter fluid
• Carburetor cleaner

Instructions

1. Make sure the saw has fresh gas and enough oil, then remove and clean the air filter by slapping the felt band across your palm or other flat surface. Pour a little gasoline onto the filter and clean with an old toothbrush, or replace it if it is old or too dirty to clean.

2. Check that the chain slides freely around the bar and isn’t caught on anything. Release the chain brake and try starting the saw. If the saw starts but dies consistently, adjust the high and low rpm needle valves.

3. Make sure the saw has air compression by pulling on the starter cord; if the saw has compression, the engine which will make a whirring or chugging noise. The cord shouldn't be too hard or too easy to pull. If it is, take off the side cover with the screwdriver and make sure the pull cord is attached properly. Replace the pull cord if it is frayed or broken.

4. Check the chainsaw’s spark plug if the saw has compression but still won’t start. Remove the rubber plug wire from the spark plug. Pour a little diesel gasoline over the spark plug and clean it with an old toothbrush. Screw the spark plug back in place, but don’t attach its rubber plug wire; let it hang loosely near a metal part on the saw’s engine block.

5. Pull the starter cord and look inside the plug to see if there is a spark. If there isn’t one, replace the spark plug and test again. If you still don’t see a spark, remove and replace the starter’s coil or the starter.

6. Confirm that the saw is getting fuel to the engine. Not enough fuel may cause the saw to idle and die or die while throttled. Remove the air filter cover and air filter. Hold your finger on the throttle to open the carburetor (the little metal flap that opens and closes when you squeeze the trigger) and spray starter fluid into the hole.

7. Try starting the saw again. If it still doesn’t start, check the fuel line to make sure gas is flowing from the tank to the engine. If it isn’t flowing, replace the fuel line.

8. Remove, disassemble and clean the carburetor. Replace all of the seals and gaskets inside the carburetor. If it still doesn’t start after a thorough cleaning, you will need to replace the carburetor. If the saw isn't working after completing these tests, you likely have something more serious going wrong inside the engine, which will require a professional to fix.

Tips & Warnings

• A majority of a saw's problems are connected to a dirty, broken or old carburetor.

• Storing saws for a long period of time will cause stale gasoline to dry up in the carburetor.

• Always use caution when working around gasoline and sparks.

• Only maintenance saws in a well-ventilated area.

References

• Stihl Chainsaw Troubleshooting Guide
• Two Stroke Engine and Carburetor Troubleshooting
• Stihl Chainsaw Care and Maintenance Guide