Troubleshooting Your Chainsaw
How to Fix a Chainsaw
Even the best chainsaws have bad days. True, some manufacturers incorporate features into their saws to help them overcome the most common problems.
However, if your chainsaw won’t start, or if it runs poorly once it’s started, it’s time for you to do some troubleshooting.
Below are some of the most common problems people experience with starting and running both gas and electric chainsaws, along with the steps you can take to try to fix them before bringing your equipment to a service center.
Watch through the 5-video playlist above to help you troubleshoot your chainsaw, discover the underlying causes, and correct the issue(s). Click the playlist icon on the top right of the image to select a video.
Starting a Saw
Today’s chainsaws are far easier to start than the models that were available 20 or 30 years ago. However, both gas and electric saws can develop problems that can make starting them difficult, even impossible.
How to Start a Gas Chainsaw That Won't Start
If your gas chainsaw won’t start, it might be a result of one of these five issues.
1. Old or Bad Fuel
Gasoline goes bad after 30 days. By that time, the alcohol that it contains in the form of ethanol will have absorbed a significant amount of moisture from the air. Fuel that contains too much moisture simply won’t ignite or combust as easily.
Additionally, small engines aren’t meant to use fuel that contains more than 10 percent ethanol. Always fill your saw’s gas tank with fuel that has an E10 (or lower) rating.
If you suspect that old fuel might be gumming up your saw, drain the tank, fill it with fresh gas, and try starting it again.
2. Incorrect Ratio of Fuel to Oil
All chainsaws have 2-cycle engines, meaning that the engine uses a mixture of fuel and oil that you combine before pouring into the gas tank. Your saw’s product manual will tell you what ratio of fuel to oil you should use if you’re not using a premade mix.
If you’ve combined them in the incorrect ratio, drain the tank and replace the liquid with the proper mixture.
3. Bad Spark Plug
A spark plug that’s dirty, worn, or cracked won’t spark and ignite the engine’s fuel. Check your plug and replace it according to the manufacturer’s schedule. Remove it, clean it, and check the size of the spark plug gap against the manufacturer’s recommendations.
4. Worn Starter Rope or Pull Rope
The starter rope on a gas chainsaw will naturally grow worn with use. When it frays (and certainly when it breaks), it can make starting your saw a challenge.
To replace your chainsaw’s pull rope, disconnect the spark plug and remove the starter housing on the side of the saw. Unwind the old rope from the starter recoil pulley. Insert the new rope into the pulley, secure it with a knot, and thread the loose end through the housing. Attach the pull handle to the end that’s been threaded through the housing, pull the rope tight, and wind the rope around the pulley about three times.
5. Cold Weather
Your engine needs to be warm in order to fire and start. If you’re trying to start your saw in cold weather, try closing the choke to give the engine a super-concentrated burst of fuel.
How to Start an Electric Chainsaw
Corded chainsaws and cordless or battery chainsaws are known for being easy to operate, but sometimes even they run into trouble. If your electric chainsaw won’t start, try examining it for these issues:
- Not pressing the safety button at the same time as the trigger
- Tripped electrical breaker (for corded chainsaws)
- Frayed or damaged electrical cord (for corded chainsaws)
- Bad or undercharged battery (for cordless chainsaws)
When it comes to corded electric chainsaws, it's vital to use the proper electrical cord for performance and safety. If you try to use a long cord with an undersized gauge, you’ll find that your saw won’t run well. This is because the cord is too thin for its length, and the electrical current is meeting too much resistance. Always use a 3-prong outdoor cord of the length and gauge recommended by the manufacturer.
Chainsaw Runs or Cuts Poorly
Congratulations on getting your saw running! However, if your saw is running but still experiencing some difficulties, try out the chainsaw repair tips below.
Gas Engine Idles Roughly or Stalls
If the sound coming from your gas chainsaw isn’t smooth and consistent, your saw might need a cleaning. Clean its air filter and spark plug, and check to make sure the plug is in working condition.
Chain Won't Move
If your electric or gas saw’s chain won't turn around the bar, chances are that the chain brake is stuck.
On some saws, resetting the chain brake is as simple as pushing in on the side cover of the saw’s body with one hand, and pushing the chain brake forward while grabbing the top handle with the other. You’ll hear a click when the brake has been reset.
Loose, Rattling Chain
If your chain turns around the bar but rattles or hangs loose as it turns, the most likely solution is that you need to adjust the chain’s tension.
Adjust the tension after every 15 minutes of use, but never adjust it while the saw is running or while it’s hot—the saw needs to cool so that that metal in the chain contracts and gives you a proper fit without bending your bar.
To tension your chain, loosen the two bar nuts on the side of the saw’s body. Hold the nose of the bar to lift it slightly, and use a flat head screwdriver to turn the tensioning screw. (The tensioning screw can be found in different places on different saw models, including between the bar nuts, on another section of the clutch cover, or on the powerhead next to the bar.)
Release the bar and tighten the bar nuts. Check that your chain is tight enough by lifting it out of the bar groove—the drivers should snap back into the groove when the chain is released. Use your screwdriver to push the chain along the bar and check that it moves freely.
If your chain has been properly tensioned but is still sagging, check the sprocket on the side of your saw for any signs of wear or damage.
Chainsaw Cuts Slowly
One of the most frustrating problems occurs when a chainsaw cuts but cuts slowly. If this is happening, you also might notice that your saw produces a lot of sawdust. This isn’t ideal; a chainsaw in top shape will produce small wood chips when it cuts, not sawdust.
A slow-cutting chainsaw is a sign that you might need to sharpen or replace your chain.
Chain Makes a Crooked Cut
If your saw doesn’t make a neat, straight cut, sharpening might once again be the issue. However, a crooked cut can be a sign that your chain has been sharpened incorrectly. Resharpen your chain, taking care to file all the cutters at the same angle. Don't forget to file the depth gauges at the same time!
Another issue that could cause a crooked cut occurs when the rails on either side of the bar’s chain groove have been worn down unevenly. When this happens, your safest bet is to replace your bar.
After Troubleshooting Your Saw
If these quick maintenance and chainsaw repair tips don't solve your problem, your next step is to contact a manufacturer-authorized service center. Service professionals at these shops will be able to consider the steps you’ve already taken and use their expertise to diagnose the problem.
But if your saw isn’t working properly, don’t be quick to write it off as broken. Often all it needs is a little bit of troubleshooting to work smoothly and efficiently.
NEXT: How to Maintain Your Chainsaw