There are some unexpected factors that can prevent your Stihl MS250 from starting, even when it’s only been used a few times or is fresh out of the box. Often, the root cause can be traced back to a lack of familiarity with the fundamentals.
Before resorting to costly dealer visits and service fees, take a moment to explore this article. Here, I’ll outline common issues that may be affecting your machine, some of which you might be able to address on your own.
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.
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, I’ve 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.
Proper compression is essential for the spark and fuel systems to work effectively, preventing air leaks from occurring. If there are air leaks in the engine or air system, it can cause the engine to malfunction or even fail prematurely.
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 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.
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.
To fix such a chainsaw 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 or why your Stihl chainsaw won’t idle, and it’s not always because the engine is broken. To ensure a smooth and safe operation of your machine, it’s essential to have a thorough understanding of it. This is why I strongly advise taking the time to read and fully comprehend the manual.
Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
