How To Fix Common STIHL MS 391 Problems [2023]

Stihl MS 391 is a powerful chainsaw that is popular among homeowners and professionals. It has a high power-to-weight ratio and is designed to handle tough cutting tasks.

Some Common Stihl Ms 391 Problems are Starting Issues, Overheating, Cutting Problems, Oil Leaking, Loud Vibration, Chain Brake, Poor Performance, Chain Tension issues, Fuel System Problems, Ignition system issues, Choke Malfunction

If you are facing issues with your Stihl MS 391, this article is for you. In this guide, I will discuss the common STIHL MS 391 problems and provide solutions to help you troubleshoot and fix them.

Common Sthil MS 391 Problems

Starting Problems

One of the most common problems with the Stihl MS 391 Chainsaw is difficulty starting the engine. This may be caused by several factors, such as a clogged air filter, a faulty spark plug, or a dirty carburetor.


To fix this problem, first, check the air filter and clean it if it’s dirty. Next, check the spark plug and replace it if it’s worn out. If the problem persists, clean the carburetor and make sure that the fuel lines are not clogged.


Another common problem with the Sthil MS 391 is overheating, especially during extended use. Overheating may be caused by a dirty air filter, a clogged muffler, or a damaged cylinder.

For Solution, first clean the air filter and the muffler. Next, check the cylinder for any signs of damage or wear and replace it if necessary. Also, make sure that you are using the correct fuel-to-oil ratio as specified in the manual.

Cutting Problems

If your Sthil MS 391 is not cutting as it should, there may be several reasons for this. It could be due to a dull or damaged chain, a loose chain tensioner, or a damaged guide bar.

To fix this problem, first, inspect the chain for any signs of damage or wear. Sharpen or replace the chain if necessary. Next, check the chain tensioner and adjust it if it’s loose.

If the problem persists, inspect the guide bar for any damage or wear and replace it if necessary.

Oil Leaking of Stihl ms 391

ms 391 oil leaking

Oil leaks are a common problem with the Stihl MS 391. They may be caused by a damaged oil seal, a loose oil cap, or a damaged oil line.

To solve this problem, first, check the oil seal and replace it if necessary. Next, tighten the oil cap to ensure a tight seal. If the problem persists, inspect the oil line for any damage or wear and replace it if necessary.

Loud Vibrations

Excessive vibrations can be annoying and may cause discomfort during use. They may be caused by a loose or damaged chain, a worn-out or damaged guide bar, or a loose engine mount.

first, inspect the chain and guide bar for any damage or wear. Replace them if necessary. Next, check the engine mount and tighten it if it’s loose.

Chain Brake Of Ms 391

Any chainsaw, including the Stihl MS 391, must have a chain brake as a necessary safety feature. Failure of the chain brake can be hazardous and raise the possibility of injury. A worn-out or damaged brake band is one typical reason for chain brake failure. You must change the brake band to resolve this issue.

Ms 391 Poor Performance

Performance problems with the Stihl MS 391 are another frequent problem. This may show up as a loss of power, a reduction in cutting capability, or an increase in fuel usage. A blocked or dirty carburetor is one potential reason why performance is low. You can either completely replace the carburetor or clean it with a carburetor cleaner to repair this.

Chain Tension Issue

Problems with chain tensioning may also arise for users of the Stihl MS 391. A loose chain could result from this, which would be risky and more likely to cause harm. Check the chain tension frequently and make adjustments as needed to resolve this issue. If the chain is broken or worn out, you can also replace it.

Ms 391 Fuel System Problem

The Stihl MS 391 chainsaw includes a fuel system as a standard component. You might have difficulties starting it, getting it to perform well, or it might overheat. A clogged fuel filter or carburetor is one typical source of fuel system problems. Clean the gasoline filter or carburetor as needed to fix this issue.

Ignition System Problems

The Stihl MS 391 engine’s ignition system is in charge of starting and operating it. You can encounter beginning or performance problems if it is not operating properly. A bad spark plug or ignition module is one potential root of issues with the ignition system. Replace the problematic part with a new one to resolve this.

Choke Malfunction

The choke is a crucial part of the starting system on the Stihl MS 391. You can have trouble starting the engine if it isn’t working properly. A clogged or dirty choke valve is one typical reason for choking issues. Clean the choke valve using a carburetor cleaner to fix this issue.


The Stihl MS 391 is a reliable and powerful chainsaw, but like any other tool, it may develop problems over time. Starting problems, overheating, cutting problems, oil leaks, and excessive vibrations are some of the common problems that users may face.

By following the solutions outlined in this guide, you can troubleshoot and fix these problems and get your Stihl MS 391 running smoothly again.

Remember to follow the maintenance schedule outlined in the manual to prevent problems from occurring in the first place.

Common FAQs

Can I use any type of oil in my Stihl MS 391?

No, you should only use two-stroke engine oil that is specifically designed for chainsaws.

How often should I sharpen my ms 391 chainsaw chain?

It depends on how often you use it and the type of wood you are cutting.

How do I adjust the chain tension on my Stihl MS 391?

To adjust the chain tension, loosen the nuts on the side of the chainsaw and use the tensioning screw to tighten or loosen the chain. Once the tension is correct, tighten the nuts back up.

How often should I clean the air filter on my Stihl MS 391?

You should clean the air filter after every five hours of use or more frequently if you are working in dusty or dirty conditions.