Having a seized chainsaw engine can not only be annoying, but it can hinder your work. If, after repeated attempts, your Stihl chainsaw engine just won’t start, you are dealing with a seized chainsaw. Thankfully, we have some helpful tips to quickly get you back to sawing.
You can fix a seized Stihl chainsaw engine by ensuring that it has fuel and applying the choke position if you are in cold weather. You may also need to clean or even replace the spark plug or the carburetor to get the chainsaw to start again.
Let’s get into more detail about these fixes and help you get your chainsaw working again.
1. Make Sure It Has Fuel
The most common reason a chainsaw won’t start is that it has run out of fuel. This may seem obvious to some who have used gas-powered machines before, but chainsaws can be more difficult to keep fueled. Not only does your chainsaw need fuel to start, but the fuel needs to be fresh.
The need for fresh fuel may seem odd, but this is what your chainsaw needs to remain usable and start properly. This is because your chainsaw does not use typical gasoline to power it. To be efficient, chainsaws require a mixture of gas and oil. The gas powers the chainsaw, while the oil provides much-needed lubrication.
Because of this combination, some of the ingredients of your oil and gas mixture will evaporate over time. So, just because you left fuel in the chainsaw the last time you used it doesn’t mean it still has plenty left. If you have trouble starting up your chainsaw, make sure that there is plenty of fuel available.
The evaporation of some of the ingredients can also cause the remaining mixture to become thicker and stickier (source). This is why fresh gas is also vital.
The thick and sticky substance left over from unchanged gas will prevent your chainsaw from functioning properly. So, not only do you need to check the amount of oil, but you should also replace the oil regularly.
2. Replace or Clean the Spark Plug
Another common reason that a Stihl chainsaw may not start is the spark plug. When you attempt to start your chainsaw, the spark plug will react by providing a spark that ignites the gasoline inside the chamber, allowing the chainsaw to start (source).
So, if you are trying to start your chainsaw without any luck, it may be because the spark plug isn’t igniting.
The spark plug can stop working properly if it needs replacing or just needs a good cleaning. First, you should try to clean the spark plug and see if that allows it to work again.
As you use your chainsaw, the spark plug will continue to ignite the gas. Over time, the mixture of the spark meeting the gas can cause corrosion to build up on the spark plug.
Too much corrosion can block the spark plug, causing it to no longer ignite when you try to start the chainsaw. If this is the case, cleaning the spark plug may be enough to remove that corrosion and get it working again.
So, use a steel brush to remove the corrosion buildup from the spark plug. If this doesn’t work, you will need to replace the spark plug altogether.
3. Choke Position
Sometimes your chainsaw can seize when the engine is too cold to start. This is an issue that will come and go as the weather changes, but it can certainly affect whether or not your chainsaw starts. Thankfully, the choke position can help your chainsaw start even when it’s cold outside.
Without the choke position activated, you may not be able to start the chainsaw in cold weather. The choke position allows more fuel to reach the engine, which your chainsaw needs when the engine is cold. Without that extra fuel, the engine will not be able to start.
If you start a chainsaw in hot weather, the choke position can harm it. The extra fuel, which it doesn’t need for a warm engine, will only flood the engine. So, ensure your chainsaw is set to the choke position when attempting to start it only during the colder months.
4. Unclog the Carburetor
The carburetor is a vital part of the process of starting a chainsaw. It is what mixes the fuel and the air that allows the engine to start.
The problem is that the fuel can sit there for a long time if you haven’t used the chainsaw for a while. As we discussed above, fuel left sitting can become thicker and even sticky due to ingredients evaporating over time.
The changing consistency of the fuel allows it to clog the carburetor and prevent it from doing its job. So, we recommend cleaning the carburetor before using your chainsaw, especially if it has been a while since you last used it.
The best way to unclog the carburetor is to drain it first. You want to make sure all the old fuel is out of there as the consistency is now probably not ideal for starting the chainsaw.
Once you drain the fuel, you will need to clean the remaining fuel out of the carburetor. Do this with a carburetor cleaner and a clean rag.
If your chainsaw has gone for too long without running, you may have fuel left over that you can’t get off. If this is the case, you may need to replace the carburetor for the chainsaw to start (source).
5. Fix the Flooded Engine
If your chainsaw doesn’t start with our fixes above, you may be dealing with a flooded engine. If the engine floods, it can affect multiple parts of the chainsaw. So, it is best to deal with this as quickly and efficiently as possible.
Using the primer is a vital part of starting your chainsaw, but you can overdo it. If you push it too much, it can cause the engine to flood, preventing the chainsaw from starting. This is fairly easy to deal with as all you need to do is drain the engine, refuel the chainsaw, and start again. But it can lead to other problems as well.
A flooded engine left undrained can cause the spark plug to no longer work or even clog the carburetor. So, it is important to ensure you only prime as necessary.
I’ve also written a complete guide on adjusting a Stihl chainsaw carburetor. Click on the link to learn more.
Final Thoughts
There can be many possible reasons your chainsaw engine may seize, but you can fix the issue yourself most of the time. If none of these solutions help your chainsaw, you may need to take it to an expert, or it may just be time to replace it.