Why Your Stihl Chainsaw Won’t Start + Troubleshooting Tips

Stihl chainsaw compression demonstration

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Stihl chainsaws are lavish and yet are valuable investments to any woodworker, so it’s definitely upsetting to find out that your high-priced tool suddenly stopped working. 

We’ve had the same problem, so here we rounded up the common issues and troubleshooting procedures you can do when your Stihl chainsaw won’t start.  

Common Issues with Stihl Chainsaws

Stihl chainsaw and fuel can

Here are the Stihl chainsaw parts and their recurring problems, according to most users:

As shown, most of these issues are common and not limited to Stihl chainsaw units only. Below you will find the top issues involving these components as well as a few troubleshooting tips.

What Causes a Stihl Chainsaw Not to Start + How to Troubleshoot

Issue #1: Bad Spark Plug

Faulty wiring connections are a common culprit to a tripped ignition module, causing a spark on the plug. When a bad spark plug ignites the fuel, it floods the chainsaw deterring the engine from starting. The common problem lies in the choke open, causing the flooded engine. 

chainsaw defective spark plug

How to Fix

Saws need enough fuel inside when generating a spark, but too much fuel can lead to a flooded saw and problems with the ignition module. To fix engine floods in a Stihl chainsaw, use a socket set to take out the spark plugs from the cylinder head and dry it with microfiber cloths.  

Also, inspect the electrode gap. If the tip of your plugs has turned black already, then it’s an indicator that your spark plug wire needs to replacement right away. You can also sand the spark plugs or bring the damaged part to a home improvement store to match it with a replacement.

This method is also used to repair a chainsaw that starts but then stops when gas is applied.

Issue #2: Worn Out Rewind Spring

Another cause of trouble in starting the engine is a worn-out rewind spring. The rewind spring recoils the string with the pulley intact when you pull the starter rope, but broken rewind springs won’t do as much job to the combustion chamber. 

chainsaw rewind spring

Most would even try to haul the rope multiple times and still end up with no combustion. 

How to Fix

Pull the starter and check for tension. Tension on the spring will prevent the rope from getting pulled or starting recoil. Disassemble the rewind spring and fix the rope, so it does not get stuck and create unnecessary tension when pulling the rope. 

When replacing a worn-out rewind spring, ensure that the chainsaw engine has cooled off to prevent burns when replacing the broken wires.

Issue #3: Clogged and Dirty Carburetor

When you don’t drain the fuel on a chainsaw after use, the evaporated gas leaves a thick and sticky residue that is often the culprit of a dirty carburetor. 

Stihl chainsaw carburetor

The fuel blocks the carburetor and intercepts the engine from starting, and if this continues, you’ll have to replace the whole carburetor.

How to Fix

Carburetor problems are common, even to the most efficient Stihl chainsaws. To fix a clogged carburetor, use a carb cleaner to break up the residue. If a carburetor cleaner doesn’t unclog the fuel, you can try rebuilding it with a carburetor repair kit. But if there’s still an unruly clog, the only option left is to replace the entire carburetor. 

Issue #4: Bad or Old Fuel

Fuel intake has a lot to do with machine maintenance and what may be causing your Stihl chainsaw to stall. Fuel intake problems, like dirty or clogged fuel, can damage fuel flow, prompt an engine to stop working, and restrict airflow in the cylinder. 

adding fuel to Stihl chainsaw

How to Fix

Inspect the fuel tank, and clean and refill the gas tank with a fresh gas mix. Check for the other parts of the gas tank, such as the rims, as gas will snip at these areas when left for a long time. 

Use mild detergent to clean the clogged fuel tanks, and pair it with a small brush for the stubborn debris or gas stains on the cylinder.

Issue #5: Loose Fuel Lines

The chainsaw engine will most likely get idle with fuel leaks, often brought about by loose fuel hoses. Calibrating your fuel lines for a tighter grip and hold is more inexpensive than calling a mechanic every time it dies out. 

How to Fix

Our experts tried to fix loose fuel hoses, and the key to making this task handier for anyone is to invest in a good pair of short and long-nose pliers. Be careful as you might tear the line when repairing these loose fuel lines. 

Issue #6: Clogged Air Filter

Like humans, chainsaw engines need air to breathe and function. Air filters on Stihl chainsaw decontaminate and prevent clogging onto your power machine, improving performance. 

Stihl chainsaw clogged air filter

However, clogged or dirty air filters will limit air into the chamber, causing the saw to stall and sputter. Replace the air filter as advised to preserve the longevity of the machine.  

How to Fix

When cleaning a dirty filter, you should include the cylinder fins and air intake slits. Cool down the engine and brush the dirty areas that are visible. Tap the fleece filters gently and make sure that the small pores get visible again before placing the cover. 

Use a Stihl Varioclean or soapy water for stubborn dirt on air filters.   

Issue #7: Compression Problems

Proper compression is essential for efficient collaboration amongst the spark, cylinder, and fuel systems. 

One of the complex yet most common reasons why a Stihl chainsaw fails to start is the compression issues brought about by air leak or clogged fuel from evaporated gas. Unregulated compression can cause the piston to seize the cylinder, decreasing the engine life. 

Stihl chainsaw compression demonstration

Check your chainsaw for possible compression issues like an air leak. Lay the chainsaw flat and tow the starter rope to check for compression. Try taking the plug out to air out the cylinder. 

Your chainsaw is on low compression if you notice the rope extending when you draw it. Getting help from a professional mechanic is the best option to fix compression. 

When to Consult a Repair Professional

Suppose you have checked all the common problems our experts have enumerated and still do not find your chainsaw working properly. In that case, it’s best to bring your saw to a professional mechanic for more specific repairs. 

person repairing a chainsaw

There may be more complex issues with the engine itself or compression problems with the starter, and professional help is the only advisable fix.  

How to Start a Flooded Stihl Chainsaw

Using the chokes on a Stihl chainsaw properly eases cold starting. Once the choke is closed, the carburetor releases extra fuel into the chamber. 

The most common mistake chainsaw users make continuing to pull the starter after the standard three to four pulls, flooding the engine with too much gasoline. 

checking a chainsaw's flooded engine

Here’s an easier fix instead of waiting for the fuel systems to drain.  

Step #1: Switch to Cold Start Position

Break on the chain, and turn the choke off to decrease resistance. Switching to a cold start makes starting a flooded Stihl chainsaw that won’t idle much easier. 

Move the selector back to the furthest back position by pressing the safety catch and trigger the throttle quickly. Disassemble the top cover, plug, and control lever.  

Step #2: Inspect the Spark Plug for Damages

One telltale sign of damage in a spark plug is chunky carbon build-ups on the ends spanning the gap. A faulty spark wire can cause your engine to sound rough or not start. Unscrew the plug using the provided wrench. Clean these parts with a wire brush with little gas. 

Stihl chainsaw defective spark plug

Inspect for possible leaks, and wipe the wet spark plugs. If there are damages like ceramic cracks, replace the spark plug. Also, check for broken wires that can lead to trouble starting the engine. 

Step #3: Switch to Warm Start Position

Move the master control directly to the run position for a warm start.

FAQ

Are Stihl Chainsaws Powered By a Mix of Gasoline and Two-Cycle Oil?

Stihl Chainsaw engines run on a mixture of lubricating oil and gasoline. However, you have to reach the correct ratio for efficiency, or else you’ll end up with a poor-performing engine. Mixing correctly also prevents piston seizing and expensive engine repairs. The expert fuel-mixing proportion is 50:1 oil: gas. 

Is there a trick to starting a Stihl chainsaw?

To start a Stihl Chainsaw, adjust the Stihl chainsaw carburetor by releasing the primer bulb twice. Shift the lever to a full choke position three to four times. And draw the starter rope six times maximum to start the engine.

Conclusion

Two of the most common causes why a Stihl chainsaw won’t start are worn-out carburetors or a bad spark plug. However, the complexity of this power tool can also confuse any woodworker on what actual issue their chainsaws might have. 

The above tips give you leverage to fixing stubborn Stihl chainsaw units, but if you still encounter problems, a pro-help should be the best option. You should take it to your local Stihl dealer to have it repaired.

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

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