Chainsaw Dies After Letting Off the Throttle (Why + How to Fix)

If you choke your chain saw, strike it up, let it warm up, and then begin cutting, you’re off to a good start. Now, if you let go of the throttle, your chainsaw should power down, and the chain should stop. Well, that’s what’s supposed to happen anyway. If you find that as you release the throttle your chainsaw dies, then you probably have some kind of tuning issues.

So, let’s take a close look at chainsaw tuning and see what you can do to stop your chainsaw from dying after letting off the throttle.

Chainsaw Dies After Letting Off Throttle (The Short Answer)

You will find three carburetor adjustments on the side of your chainsaw: low, high, and idle. The low carburetor adjustment screw determines how much fuel will enter the carburetor at low speed when the throttle is not engaged and will, in turn, determine the engine speed. If this adjustment is too low, the engine will stall when you let off the throttle.

Why Does the Chainsaw Have This Problem

One thing you’ll notice when using a chainsaw is that there is a lot of vibration. This vibration can vibrate the carburetor adjustment screws and cause the carburetor to become out of tune. Now, a lot of chainsaws have these screws pass through a plastic washer to try to prevent them from loosening, but at some point, even this preventative measure isn’t enough. So, tuning is needed on even the best chainsaws.

Diagnose the Carburetor Low, High, & Idle Adjustment

Whenever you need to adjust the low setting on your chainsaw’s carburetor, it’s best to test all three adjustments. This is because the carburetor needs to be tuned, not just the low setting. So what are the three adjustments for, and how do you test them? Let’s take a look.

Low Chainsaw Carburetor Adjustment

The low adjuster allows you to adjust the air/fuel mix at idle speed. So, if you tighten the adjustment, the engine will speed up, and if you loosen the adjustment, the engine will slow down. Again, if you loosen the adjustment too much, the engine will stall.

Testing the Low Chainsaw Carburetor Adjuster

A quick way to test a low-speed setting is to do a dump test. So, start your chain saw and allow it to idle for 20-30 seconds to warm up. Then lift the chainsaw, so it is level, followed by quickly lowering the bar tip down to the ground. If you hear a dip in an alteration in the engine sound, then the low-speed setting is allowing too much gas into the carburetor. If your chainsaw just stalls with or without this test, then you’ll know you need to make an adjustment.

High Chainsaw Carburetor Adjustment

The high adjustment screw will determine how high the engine can rev. So, if the adjustment is too high, then the engine will over speed, whereas if the adjustment is too low, you’ll reduce the top engine speed and lose power.

Testing the High Chainsaw Carburetor Adjuster

Pull the throttle fully and listen to the engine sound. If the engine is revving very high and squeals, then the adjustment is too high. If the engine sound appears to be lower than it should be, then the adjustment could be too low.

Idle Chainsaw Carburetor Adjustment

The idle adjuster is really a fine adjustment of the low-speed setting and is mainly a safety feature of the chainsaw to stop the chain from advancing when the saw isn’t in use. So, if the adjustment screw is set too high, then the chain will advance without the throttle engaged.

If the adjustment screw is too low, then the chain will stop, but the engine may struggle. Therefore finding the middle point is key.

Testing the Idle Chainsaw Carburetor Adjuster

Start up your chainsaw and let it idle. If the chain inches forward, then the idle adjuster needs to be adjusted. This is because the engine is running too fast, and the clutch is engaging.

How to Fix a Chainsaw that Dies After Letting Off Throttle (Step-by-Step)

For these examples, I will look at Stihl chainsaws. If you look at the adjustment screw holes on the side of the chainsaw, you’ll find three adjustment screw holes labeled H, L & Idle. In addition, you’ll see that the H and L have adjustment information.

For example, the Low will show an anticlockwise ¼ turn, the High will show an anticlockwise ¾ turn, and the Idle usually doesn’t show anything. These are the standard adjustments you’ll need to make for a new chainsaw. As chainsaws get older, these adjustments will begin to alter a bit.

Now, it doesn’t alter too much, but enough that you’ll need to fine-tune your carburetor outside of these guides. So let’s take a look at the tuning process.

Adjusting the High Setting

Use a small screwdriver to adjust the high screw by turning the screw clockwise. Tighten the screw until it stops. Don’t over-tighten the screw. Then turn the adjustment screw anticlockwise as per the label. In this case, it’s ¾ of a turn. Then start your chainsaw. Now rev your chainsaw engine and repeat the test from above, listening for the engine sound.

Use your screwdriver and make adjustments until the engine sound is in the middle ground, not too high, not too low, and not squealing. Finally, switch off the chainsaw.

Adjusting the Low Setting

Use your small screwdriver and fully turn the screw clockwise, remembering not to tighten the screw. Then adjust the screw as per the Low label. In this case, ¼ turn anticlockwise. Now start your chainsaw.

Next, use your screwdriver and adjust the Low screw to either increase or decrease the engine speed. You’ll aim to have the Low speed low enough so that the engine is above stalling. You can repeat the dump test to test your low speed.

Adjusting the Idle Setting

So with the low and high set, you can move onto the idle. So adjust the idle screw just lower than the point at which the chain starts to turn.