Why Your Stihl MS250 Won’t Start + Top Tried & Tested Solutions

Stihl MS250 with low compression

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Our experts find surprising reasons why your Stihl MS250 won’t start, even if you’ve only used it a couple of times or if it’s brand new. Most of the time, the reason stems from a lack of knowledge of the basics. 

Check this article to find out what probable errors your machine has, before rushing into your dealer only to pay service fees for fixes you can actually do by yourself. 

Common Reasons Why Your Stihl MS250 is Unable to Start

Reason #1: Ignition System Issues

Faulty ignitions are the main culprit why your Stihl chainsaw is unable to start. Check all points that could be ceasing the engine from combusting, such as corroded spark plugs, faulty wirings, broken wires, or even improper air gaps. 

Stihl MS250 ignition system

Reason #2: Fuel Issues

Most of the starting problems ignite from dirty fuel system parts. The vacuum pressure on the carburetor sucks fuel when the crankshaft starts to spin, and it will require enough fuel inside the cylinder to work efficiently. 

Reason #3: Carburetor Issues

With careful inspection, our team found the common perpetrators of carburetor issues which is also present in other models like Stihl MS440 saw. Filthy bores and jets, improperly placed needle valves, and plunged levers are the culprits that halted the fueling process. These parts are found in the three chambers that compose the carburetor— the metering and mixing section and the fuel pump. 

Reason #4: No Proper Compression

Compression is generated when the piston creates an up-down movement in the cylinder. 

Stihl MS250 with low compression

Without proper compression, the spark and fuel systems won’t work properly, causing air leaks to occur. Air leaks in the engine or air system can cause the engine to reach its end term instantly. 

Tried and Tested Fixes to Stihl MS250 Starting Problems

Fix #1: Inspect the Parts of the Ignition System

Before disassembling your Husqvarna or Stihl chainsaw to inspect the parts, this quick tester from our tool experts will help you check if it’s the sparks that are causing your Stihl MS250 to malfunction. Disconnect the positive wire so it isolates the coil from the electrical system. 

Pull the wire out, and check for sparks. If there are no sparks, then the ignition coils are the problem, and replacing the ignition module is the best solution.

Fix #2: Repair Important Wiring and Connections

Inspect the wire conditions that may be causing the mishap on your chainsaw. If you notice disconnected linings,  worn-out cables, or misaligned connections, then a repair is utmostly needed to help your machine function as desired again. 

rebuilding wiring system of Stihl MS250

Make sure to insert the new wires on the ignition module tabs before reinstalling the recoil assembly. 

Fix #3: Clean Fuel Tank and Filters

When fuel tanks and filters are contaminated with dirt, it can cause clogs, restricting fuel flow. It’s advised to clean and replace all these fuel parts before checking in the internal engine. 

Also check possible loose fuel holes, dirty lines, or clogged fuel tanks and only use hot water and mild detergents in cleaning to avoid other possible problems to occur.

Fix #4: Unclog Carburetor

Disassemble the carburetor and unclog the holes by blowing them with air. Most of the time, the only issues with carburetors are clogs and dirty filters. 

Stihl MS250 carburetor

To fix such an issue, clean the entire carburetor and if you see most parts wearing out, it’s also best to install an upgrade kit, to save you costs from buying a new one. 

Other Important Tips and Reminders

Tip # 1: Do regular cleaning and maintenance

Use proper cleaning materials and detergent when doing maintenance to your Stihl chainsaw. Clean and visually inspect your machine including checking issues on your chainsaw teeth before starting work. Also, check whenever the tank is refilled. 

Other machine parts such as the fuel tank and cylinder fins can become clogged within a month, depending on the use. This means that monthly checks are a requisite maintenance routine too. 

Tip #2: Follow Proper Starting and Operating Procedure from the Manual

Any wood-cutting tool has an array of safety precautions that should be followed to avoid injury while operating the machine. Wear safety gears and pay attention to reactive forces or kickbacks that can be dangerous too. 

While lending your chainsaw may sound generous, do not do so without handing them the instruction manual as any misuse may lead to personal and fatal accidents [1]

FAQ

How do you prime the Stihl MS250?

To prime the Stihl MS250, press the flexible plastic bulb or the starter rope with your thumb several times to prime the fuel system. 

How do you unflood the Stihl MS250?

To unflood the Stihl MS250, level the chainsaw on a flat surface and activate the chain brake. Clean the electrode with a rag, and pull the wire with a spark plug wrench tool. 

Conclusion

As exemplified above, there are a lot of probable causes why a Stihl MS250 won’t start, and it’s not always because the engine is broken. Having a full grasp of your machine is necessary, which is why reading and comprehending the manual is imperative for a seamless and safe operation. 

Robert Johnson is a woodworker who takes joy in sharing his passion for creating to the rest of the world. His brainchild, Sawinery, allowed him to do so as well as connect with other craftsmen and women. He has since built an enviable workshop for himself and an equally impressive online accomplishment: an extensive resource site serving old timers and novices alike.
Robert Johnson