It’s frustrating when you’re ready to start your project, but your chainsaw won’t cooperate. You might be holding the trigger, but the motor won’t rev up. If that’s the case, read on and find out why a Stihl chainsaw does not rev up even when you pull the throttle with enough force.
When a Stihl chainsaw trigger won’t rev up, some of the most common culprits include M-Tronic not working correctly, dirty air filter or fuel filter, and wrong carburetor adjustments. You’ll need to clean the dirty components, adjust the carburetor, or reset M-Tronic to fix the problem.
In this article, I’ll share some of the most common culprits for a Stihl chainsaw not reaching its full power despite activating the trigger. More importantly, I’ll also discuss the best solutions.
1. M-Tronic Not Working Properly
Stihl chainsaws pack state-of-the-art features to deliver optimal performance, even in the most demanding tasks. An example of this is the M-Tronic technology. It makes automatic adjustments in the fuel and air mix, depending on what a specific job requires (source).
While M-Tronic is a great feature, there are times when it won’t work as it should. And when this happens, the biggest indicator is your chainsaw refusing to rev up.
How To Fix It
The easiest fix is to reset M-Tronic. Below is a quick step-by-step guide on how you can do so:
- Start by removing the sheath.
- Ensure the chain brake is engaged.
- Set the machine in a cold start position and run for 90 seconds. At this point, you shouldn’t press the throttle or accelerate.
- Turn off the chainsaw.
- You’re now done resetting and recalibrating the machine. Try pressing the trigger and see if your tool revs up. If it doesn’t, look at other possible causes.
Learn more about what M-Tronic is and see how to reset it with this YouTube video:
2. Dirty Air Filter
As the name implies, an air filter’s main job is to filter the engine’s air. It removes dirt and debris that could reach or damage the engine and carburetor. Hence, once the air filter is dirty, some of the components won’t work correctly (source).
Cleaning the air filter might resolve a Stihl chainsaw trigger not revving up.
How To Fix It
Even if the air filter isn’t exposed, it accumulates dirt over time. It’s essential to clean the filter regularly to avoid this.
Here’s how to clean your Stihl chainsaw air filter:
- Find the air filter. It’s usually next to the engine or the top of the unit.
- Remove the cover and unscrew the air filter from the chainsaw.
- Mix hot water and soap in a bucket. Tap the air filter to loosen any excess dirt.
- Dip a brush in your cleaning solution and gently clean the dirt off the air filter.
- Rinse the filter in water and dry thoroughly.
- Return the air filter to its original position and cover.
3. Dirty Fuel Filter
The fuel filter is an equally crucial component in Stihl chainsaws. It prevents dirt from getting in the fuel. One of the most common signs that it needs a replacement is when the chainsaw stumbles while operating. It could also be the culprit when it won’t rev up and reach its full power despite forcing the throttle trigger.
The fuel filter is easily accessible from the gas tank, so it’s easy to clean and maintain.
How To Fix It
Retrieving the filter requires access from the gas tank, so it’s best to work when the gas tank is empty. Here’s a guide on removing and replacing a fuel filter (source):
- Start by setting the chainsaw on a flat surface.
- Take the spark plug boot out of the unit. This will prevent accidentally starting the unit.
- Remove the gas cap. If there’s still fuel inside, you’ll have to empty it first through hand siphoning.
- Use a wire and form it into a hook. Put it inside the tank, hook the filter, and pull.
- Hold the fuel line while you are cleaning the filter. Once it falls into the tank, it won’t be easy to retrieve, so you must hold it properly.
- Once you are done cleaning the filter, you can put it back in the tank, along with the fuel line. Gas up and get ready to use the chainsaw.
4. Wrong Carburetor Adjustment
The carburetor is one of the most critical components in a chainsaw. It’s responsible for metering tiny fuel quantities and mixing them with air that enters the engine. It ensures optimal engine functionality (source).
When the carburetor isn’t correctly set, the chainsaw will have the wrong mix of air and fuel. This can cause it to run poorly and start to occasionally stall and bog down. It might fail to rev up even after engaging the trigger.
Check out my guide discussing what causes Stihl chainsaw carburetor adjustment problems along with potential solutions to learn more about this.
How To Fix It
Your best bet is to adjust the carburetor. Luckily, it’s an easy task. Before you do this, you should have a clean spark arrestor and air filter. Here’s a quick guide on how you can do it:
- Start the motor of your chainsaw and wait for it to warm up.
- Adjust the idle speed screw clockwise using a flathead screwdriver.
- Set the idle screw midway at low speed. At this point, the engine will start to die.
- Engage the throttle and put a digital tachometer on the spark plug.
- Next, rotate the high-speed screw clockwise.
- Look for the setting at which the engine demonstrates the best sound. Remember that the speed the engine records must be lower than the maximum that the manual states.
Conclusion
Stihl chainsaws are known for their remarkable performance. However, they inevitably experience several problems over time, including not revving up even after engaging the throttle trigger. If that’s the case, the problem could be with M-Tronic, air filter, fuel filter, or carburetor. The solutions include cleaning the dirty parts, making some adjustments, or resetting M-Tronic.
Regularly performing maintenance on your chainsaw should prevent these issues from occurring. Ensure you set time aside every few months to clean the parts and always store the chainsaw in a clean, dry place.
