How to Fix a Non-Starting Chain Saw: A Comprehensive Guide

Chain saws are essential tools in various outdoor activities and professional settings. However, when they fail to start, it can be frustrating. This guide will help you identify and resolve common issues that prevent your chain saw from starting, ensuring that you can get back to work or enjoy your outdoor activities efficiently.

Common Causes and Solutions for a Non-Starting Chain Saw

1. Dirty Spark Plug or Electrical Component Issues

One of the most common reasons a chain saw fails to start is due to a dirty spark plug or electrical issues with the ignition system. Here are the steps to follow:

Unscrew the spark plug and examine it for any signs of fouling, such as carbon deposits or oil contamination. Clean the spark plug with a wire brush or by using a carburetor cleaner. Alternatively, you can replace the spark plug if it's damaged. Reinstall the spark plug and try to start the chain saw with the chain disengaged.

Make sure the spark plug gap is correct. Typically, a gap of .030 or as small as .016 for McCulloch models is recommended.

2. Carbon Build-up on Exhaust Filter Screen

Carbon buildup can clog the exhaust filter screen, affecting the chain saw's performance. To clean the screen:

Remove the exhaust filter screen using pliers. Heat the cherry-red carbon off with a propane pencil yip torch. Reinstall the screen and ensure it's not overfilled. The chain saw should start easily with the chain disengaged.

Be cautious during this process to avoid damaging the screen.

3. Ethanol-Based Fuel or Poor Storage

Storing a chain saw with ethanol-based fuel can lead to issues such as clogged fuel lines or a damaged carburetor. Here’s what to do:

Inspect the fuel lines and carburetor for any damage or damage from ethanol. Check the muffler for signs of mud or wasp nests, which can block airflow and prevent the chain saw from starting. Address any fuel or air-related issues by cleaning or replacing the carburetor.

4. Electrical Component Testing

To further diagnose electrical issues, follow these steps:

Disconnect the kill switch from the coil and test the spark. Check if the kill switch is activated. If it is, this could be the reason for the non-starting chain saw. Ensure the airgap between the coil and the flywheel magnet is .020″. You can use a real non-laser printed business card or double a laser-printed one to measure accurately. Remove the corroded parts of the coil and flywheel magnet and reassemble with the correct airgap.

5. Lubrication and Fuel Mix Issues

Mis-mixed fuel or oil can also cause the chain saw to fail to start. Here are some tips:

Change the fuel and oil mix to the recommended ratio. Use a fuel system cleaner like Seafoam to help clean the carburetor in past cases.

6. Coil Replacement

If the spark plug and other components are in good condition but the chain saw still fails to start, a faulty coil might be the culprit. Here’s how to check and replace it:

Test the coil to ensure it's working properly. If the coil is bad, it must be replaced. Look for signs of rust or corrosion on the magnets and the coil. Disassemble the coil and clean the magnets and the coil. Reassemble with a correct .020″ airgap and test again.

Remember, a functional coil is essential for a reliable starting system.

Conclusion

Troubleshooting a non-starting chain saw can be a daunting task, but with proper knowledge and a step-by-step approach, you can resolve most issues. Whether it's a dirty spark plug, a clogged exhaust filter, or a bad coil, the key is to methodically check and clean the relevant components.

By following the guidelines provided in this article, you can restore your chain saw to optimal working condition and continue with your outdoor activities with peace of mind. If you're still unsure, consider consulting a professional or service technician to ensure the best results.