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My Chainsaw Will Not Idle: How to Fix This

There’s nothing worse than looking forward to a great workday, only to find that due to maintenance problems with your chainsaw, the start will be delayed. Regardless of the easy maintenance of a chainsaw, chances are, they would eventually develop problems. Because of its durability, most of us expect our chainsaw to work all the time and whenever we need it to. If your chainsaw won’t idle but you need to get work done, what do you do?

My Chainsaw Will Not Idle: How to Fix This?

If the chainsaw is not responding or hard to start, then it’s an indication that there’s an issue with the fuel and air mixture. If it responds briefly, then falters and shuts off, it’s a problem caused by the idle function. Finally, if your chainsaw resounds well but dies off when working under a load, then it might also be an idle problem as well.

Use the following steps to fix the problem:

  • Clean the Air Filter
  • Locate the Idle Screw
  • Tweak the Carburetor Idle
  • Make one-Screw Idle Adjustments
  • Make three-Screw Adjustments

When you start your chainsaw, it should be able to sit idle for a while until you eventually engage the clutch, which is responsible for driving the gears and sprockets in order to spin the chain. In some cases, a 2 -cycle engine may find it hard to stay running, and this may kill the engine when not in use. There are different reasons why a chainsaw won’t idle properly. To provide more information as well as the solution to this issue, this article will address the necessary steps to take to get your tool back up and running in no time.

Why Won’t Your Chainsaw Idle?

There could be several different reasons responsible for this. The air filter might be clogged, allowing the engine to run an air-fuel mixture which will, in turn, result in loss of power creating a low throttle response. The spark arrestor may also be jammed up, and this happens when you put excess oil into the gas-oil fuel mix. This would result in plenty of unburnt substance as oil combusts at a very high temperature than gas. The soot produced will clog up the spark arrestor, preventing exhaust gasses from escaping freely. Another reason might be the spark plugs with corroded electrodes, and as you know, you can’t actually have a fire without a spark. Even if you do have a spark, it will be too weak due to the carbon buildup around the electrodes, leading to incomplete combustion of the fuel mix. This is why most chainsaw manufacturers recommend that you replace the spark plug every 100 service hours.

Also, you might want to check the fuel line and filter within the gas tank. In some cases, the ethanol (in cheaper gas) will cause the soft rubber tube that usually carries fuel from the tank to the carburetor to corrode. To check for holes or cracks in the fuel line, you can flash light into the tank after emptying it. If they’re present, then it is time to change them. While you’re at it, you might also change out the fuel filter, since they are quite cheap anyway. A corroded fuel line will allow too much air in the tank and cause the chainsaw to run lean. This only means that the chainsaw will only run at idle for a few seconds before it shuts off completely.

How to Fix a Chainsaw That Will Not Idle

If you can start your chainsaw easily, and it runs smoothly without any issue, then the idle is working just fine, and there’s no need to tamper with it. However, If the chainsaw is not responding or is hard to start, then it’s an indicator that there’s an issue with the fuel and air mix. If it responds briefly, then falters and shuts off, it’s a problem caused by the idle. Finally, if your chainsaw resounds well but dies off when working under a load, then it might also be an idle problem. Here are steps to help fix idle problems.

● Clean the Air Filter

This is an obvious place to start since the air filter gets pretty dirty. As you already know, chainsaws throw out a lot of dust and dirt, and some even run a turbo type system in which the air is directed towards the carburetor. When this happens, it’s usually left for the air filter to catch all the debris. The modern chainsaw designs all come with tool-less air filter covers, allowing them to be easily accessed. Some chainsaws come with fine mesh screens while others have a fabric or foam filter- all depends on the manufacturers.

The best way to clean the air filter is by using compressed air, but not everyone owns a compressor, so an easy alternative would be by tapping it on a solid surface to loosen all the debris. You can then use a bristled brush or a clean rag to clean it up. Different filters often have different care suggestions, but most of them are easily cleaned with warm, soapy water as soon as you tap off the excess dirt and particles. Most air filters typically last for a long time since they are designed to be durable. However, the moment you notice a hole in your filter or you see a lot of debris intake, then you’ll most likely need a new filter. Once an air filter is clogged, all attempts to adjust your idle may be complicated. It is recommended to clean air filters after five hours of run time.

● Locate the Idle Screw

All gas chainsaws often have 3 adjusting screws on the carburetor, that can be accessed without having to remove any covers. You won’t actually see the adjusters, instead, you just identify the right access port and simply insert the correct adjusting tool. The first adjuster is marked on the body cover with the letter (L) and it is the low throttle adjuster. The second, which is the high throttle adjuster is marked with the letter (H). These 2 adjusters are placed side by side as a pair and are set from the factory, hence they often require a special tool to adjust them. Yes, they can be adjusted, but it takes skills to adjust them correctly.

The 3rd adjuster is the Idle screw adjuster, marked with the letter L  or T or LA, and is often placed just above or below the other two adjusters. This 3rd adjuster is the one we need to adjust. You’ll only need a flat screwdriver for this, or something that will easily fit through the hole in the side cover. As much as you may want to, it’s not advisable to remove the air filter to gain access as it should stay fitted. This is the whole point of the access ports.

● Tweak the Carburetor Idle

On right-handed chainsaws, the idle screw is often located on the left. To be on a safe side, it is best to check the owner’s manual, or check the internet for the particular make and model you have, to locate the correct screw or screws to adjust. Either tweak a single screw or three separate screws, but in both instances, the premise is usually the same.

● One-Screw Idle Adjustments

To easily locate your starting point, start up your chainsaw and keep a flat-head screwdriver close. The T-head screws are very sensitive to turning, so you should work with your flat screwdrivers at quarter-turn increments at most, making mental notes as you go. When you’re turning the screw clockwise or counterclockwise, watch out for changes in the engine’s behavior while you’re throttling and also when idling. If your chainsaw doesn’t stop spinning when idling or it emits smoke when it idles, then it is getting too much fuel and running rich, so you’ll have to stop for a bit. On the other hand, if it is spinning too slowly, or jumps erratically when idling,  then it is getting too little fuel and needs more. Always take mental note of the position of the screw when the saw runs lean or rich.

● Three-Screw Adjustments

Three-screw carburetors are very tricky to tune, so you should be careful when adjusting the high-speed performance screw. To adjust,  locate the “LA” screw first. This screw controls the general idle-speed, and tweaking the performance is very similar to that of the single-screw carburetor adjustment highlighted above. Begin by adjusting this screw as you would for the single-screw. Then adjust the “L” screw second. The “H” screw stands for high-speed adjustment. This screw is very crucial as setting it too lean or too rich can cause serious damage to the engine. It is recommended to never adjust this screw more than ¼ turn either way. Turn the screws to know where the lean and rich points are, and then find a balance between them. You should never have to open or close a timing screw completely to the maximum or minimum. If this happens, you should probably take the chainsaw to the shop for maintenance.

Final remarks

Finally, you should test the performance while throttling and idling. Ensure that there isn’t too much smoke, and the engine purrs smoothly. Once you’ve taken all these into consideration, you should be good to go.