Stihl MS 251 Problems: Troubleshooting Guide

The Stihl MS 251 chainsaw is a popular model for home and landscaping use. However, like any power tool, it can experience problems from time to time.

Here are some of the most common Stihl MS 251 issues and how to fix them:

Full Throttle Problem

If your Stihl MS 251 chainsaw isn’t reaching full throttle, the likely culprits are a clogged air filter or a dirty carburetor. To fix this issue:

  • Clean or replace the air filter
  • Clean the carburetor

This should help get your chainsaw back up to full speed.

Keeps Shutting Down

There are a few possible causes if your Stihl chainsaw repeatedly shuts off during use:

  • Clogged air filter
  • Dirty carburetor
  • Malfunctioning fuel pump

Try cleaning or replacing the air filter, cleaning the carburetor, and checking the fuel pump. One of these solutions should stop the constant shutting down.


An overheating Stihl chainsaw is often caused by:

  • Dirty air filter
  • Dirty carburetor
  • Malfunctioning fuel pump

Clean or replace the air filter, clean the carburetor, and check the fuel pump. This should resolve any overheating issues.

Chain Brake Not Engaging

If the chain brake fails to engage properly, the likely causes are:

  • Malfunctioning chain brake
  • Loose brake band

Inspect the chain brake for issues and tighten the brake band as needed.

Won’t Start

When your Stihl MS 251 won’t start, the problem typically lies with the ignition system:

  • Defective wiring
  • Faulty spark plug
  • Malfunctioning ignition coil

Check all ignition components and repair or replace any defective parts. Other issues like a clogged air filter, dirty carburetor, or fuel supply problem could also prevent starting.

Bad Airflow and Engine Efficiency

Reduced engine power and poor performance is often due to:

  • Clogged air filter
  • Dirty carburetor

Clean or replace the air filter and clean the carburetor to restore proper airflow and engine efficiency.

Faulty Fuel Supply

Problems with the fuel supply can degrade engine performance over time:

  • Clogged fuel filter
  • Malfunctioning fuel pump

Clean or replace the fuel filter as needed. Check the fuel pump for issues and repair as necessary.

Chain Breaks Easily

If your Stihl chainsaw chain seems prone to breaking, look at:

  • Dull chain
  • Improper chain tension

Sharpen or replace a dull chain. Adjust the chain tension to specification. This should reduce chain breakage.

With regular maintenance and by troubleshooting issues promptly, you can extend the life of your Stihl MS 251 chainsaw and keep it running smoothly. Let us know if you have any other questions!

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