How to Start a Flooded Stihl Chainsaw (5 Pro Tips for Smooth Cuts)

Starting a flooded Stihl chainsaw can be a frustrating experience, especially when you’re in the middle of a job. But with the right knowledge and techniques, you can get your saw running smoothly again. This guide will provide you with five pro tips that I’ve learned over years of working with chainsaws, both professionally and as a dedicated homeowner. I’ll share my experiences, insights, and step-by-step instructions to help you tackle this common issue.

Regional needs significantly influence our approach to chainsaw maintenance and operation. In regions with colder climates, like Scandinavia or Canada, chainsaws are vital for heating homes and managing forests. Flooding can be a bigger problem in colder weather, as the fuel mixture becomes less volatile. Conversely, in tropical regions, chainsaws are essential for land clearing and agriculture, but humidity can affect fuel quality and carburetor function, indirectly contributing to flooding issues. Therefore, understanding your local climate and fuel characteristics is the first step in preventing and addressing a flooded chainsaw.

I remember one particularly cold morning in northern Minnesota. I was helping a friend clear some land for a new cabin, and his Stihl MS 291 refused to start. After several futile attempts, it was clearly flooded. The air was biting, and the wind was howling. The thought of spending hours trying to fix it in the cold wasn’t appealing. That day, I refined my approach to dealing with flooded chainsaws, focusing on quick, effective methods.

Understanding the Flooded Chainsaw

Before diving into the solutions, let’s understand what it means for a chainsaw to be “flooded.”

• Definition: A flooded chainsaw has an excess of fuel in the cylinder. This happens when too much fuel is drawn into the engine during starting, typically due to repeated attempts to start the saw with the choke engaged or a faulty carburetor.

• Key Concepts:

  • Air-Fuel Ratio: The ideal ratio of air to fuel for combustion is crucial. When there’s too much fuel, the mixture becomes too rich, preventing the spark plug from igniting the fuel.
  • Choke: The choke restricts airflow to enrich the fuel mixture for cold starts. Overuse can easily lead to flooding.
  • Carburetor: The carburetor mixes air and fuel. A malfunctioning carburetor can deliver too much fuel, causing flooding.
  • Spark Plug: The spark plug ignites the air-fuel mixture. A wet spark plug won’t produce a spark.

Pro Tip 1: The “No Choke” Pull Method

This is often the simplest and most effective method for clearing a flooded engine.

• Step 1: Identify the Problem: Confirm that the saw is indeed flooded. Typical signs include a strong smell of fuel, a wet spark plug (if you check it), and the engine refusing to start after multiple attempts.

• Step 2: Disengage the Choke: Ensure the choke is completely disengaged. This allows maximum airflow into the cylinder. On most Stihl chainsaws, this means moving the choke lever to the “run” position.

• Step 3: Full Throttle: Hold the throttle wide open. This helps to introduce more air into the cylinder, aiding in the evaporation of excess fuel.

• Step 4: Pull the Starter Cord: Pull the starter cord repeatedly and briskly. You might need to pull it 10-15 times, or even more, depending on the severity of the flooding. The goal is to clear the excess fuel from the cylinder.

• Step 5: Listen Carefully: As you pull, listen for the engine to sputter or show signs of life. This indicates that the fuel is clearing.

• Step 6: Try a Normal Start: Once the engine shows signs of life, release the throttle and try starting the saw as you normally would (choke engaged if the engine is cold).

Personal Experience: I’ve used this method countless times, often with success on the first attempt. It’s especially effective when the flooding is mild. I remember a time helping a neighbor after a storm. He’d flooded his Stihl while trying to clear fallen branches. Within minutes, the “no choke” pull method had his saw roaring back to life.

Data and Insights: In my experience, this method has a success rate of around 70-80% for moderately flooded engines. It’s a good first step because it’s non-invasive and doesn’t require disassembling any parts.

Pro Tip 2: The Spark Plug Inspection and Cleaning

If the “no choke” method doesn’t work, the next step is to inspect the spark plug.

• Step 1: Safety First: Disconnect the spark plug wire to prevent accidental starting.

• Step 2: Remove the Spark Plug: Use a spark plug wrench (typically a 19mm or 13/16 inch socket) to carefully remove the spark plug.

• Step 3: Inspect the Spark Plug: Examine the spark plug for signs of fouling, such as wetness, carbon buildup, or damage.

• Step 4: Clean the Spark Plug: If the spark plug is wet with fuel, dry it thoroughly. If there’s carbon buildup, use a wire brush or a spark plug cleaner to remove it. You can also use a specialized spark plug cleaning tool that blasts the plug with abrasive media.

• Step 5: Check the Gap: Ensure the spark plug gap is within the manufacturer’s specifications. This is typically around 0.020-0.025 inches (0.5-0.6 mm). Use a spark plug gapping tool to adjust the gap if necessary. A proper gap ensures a strong spark.

• Step 6: Test for Spark: Reconnect the spark plug wire and ground the spark plug against the engine block. Pull the starter cord and check for a strong, blue spark. If there’s no spark or the spark is weak and yellow, the spark plug may be faulty and needs to be replaced.

• Step 7: Reinstall the Spark Plug: Reinstall the spark plug, tightening it to the manufacturer’s specified torque (typically around 15-20 Nm or 11-15 ft-lbs). If you don’t have a torque wrench, tighten it snugly but not excessively.

• Step 8: Try Starting Again: Reconnect the spark plug wire and try starting the saw using the normal starting procedure.

Personal Experience: I once had a Stihl MS 261 that kept flooding after a few minutes of use. After trying the “no choke” method several times, I decided to inspect the spark plug. It was heavily fouled with carbon. After cleaning it thoroughly and ensuring the gap was correct, the saw started and ran perfectly.

Data and Insights: A fouled spark plug can significantly reduce engine performance and cause flooding. Cleaning or replacing the spark plug can restore proper ignition and improve starting reliability. The cost of a new spark plug is typically low (around $5-$10), making it a worthwhile investment.

Pro Tip 3: The “Air It Out” Method

This method involves removing the spark plug and pulling the engine over to expel excess fuel from the cylinder.

• Step 1: Safety First: Disconnect the spark plug wire.

• Step 2: Remove the Spark Plug: Remove the spark plug as described in Pro Tip 2.

• Step 3: Turn the Saw Upside Down: This helps gravity assist in draining the fuel from the cylinder.

• Step 4: Pull the Starter Cord: Pull the starter cord repeatedly (10-15 times) to expel the excess fuel. You may see fuel spraying out of the spark plug hole.

• Step 5: Let it Air Out: Leave the spark plug out for about 15-20 minutes to allow the cylinder to air out completely. This allows any remaining fuel to evaporate.

• Step 6: Reinstall the Spark Plug: Reinstall the spark plug, ensuring it’s properly tightened.

• Step 7: Try Starting Again: Reconnect the spark plug wire and try starting the saw using the normal starting procedure.

Personal Experience: I’ve found this method particularly useful in situations where the engine is severely flooded, and other methods have failed. I once had a Stihl 026 that had been left sitting for months with fuel in the tank. The fuel had deteriorated, and the engine was completely flooded. After using the “air it out” method, the saw started on the second pull.

Data and Insights: This method can be more effective than the “no choke” method for severely flooded engines. Allowing the cylinder to air out ensures that all excess fuel is removed, increasing the chances of a successful start.

Pro Tip 4: The Carburetor Adjustment (Advanced)

This method involves adjusting the carburetor settings to lean out the fuel mixture. This should only be attempted if you have experience with carburetor adjustments. Incorrect adjustments can damage the engine.

• Step 1: Locate the Carburetor Adjustment Screws: On most Stihl chainsaws, the carburetor adjustment screws are located on the side of the carburetor. There are typically three screws:

  • L (Low-Speed): Adjusts the fuel mixture at idle and low speeds.
  • H (High-Speed): Adjusts the fuel mixture at high speeds.
  • LA (Idle Speed): Adjusts the engine’s idle speed.

• Step 2: Lean Out the Low-Speed Mixture: Carefully turn the L screw clockwise in small increments (e.g., 1/8 of a turn). This leans out the fuel mixture at low speeds, reducing the amount of fuel being delivered to the engine during starting.

• Step 3: Try Starting the Saw: After each adjustment, try starting the saw.

• Step 4: Fine-Tune the Adjustment: Continue adjusting the L screw until the saw starts and runs smoothly at idle.

• Step 5: Adjust the Idle Speed: If necessary, adjust the LA screw to achieve the correct idle speed (typically around 2,500-3,000 RPM).

Personal Experience: I’ve used carburetor adjustments to fine-tune the performance of my chainsaws for different altitudes and fuel types. However, I always proceed with caution and consult the manufacturer’s specifications to avoid damaging the engine.

Data and Insights: Carburetor adjustments can significantly impact engine performance and fuel efficiency. However, they should only be performed by experienced users who understand the principles of carburetor operation. A slightly lean fuel mixture can improve starting reliability, but an excessively lean mixture can damage the engine.

Measurements and Tool Specifications:

• Carburetor Adjustment Screwdriver: Use a specialized carburetor adjustment screwdriver with a small, flat blade.
• Tachometer: Use a tachometer to accurately measure the engine’s idle speed.
• Manufacturer’s Specifications: Consult the chainsaw’s owner’s manual for the recommended carburetor settings.

Pro Tip 5: Prevention is Key – Proper Starting Technique

Preventing flooding in the first place is always better than having to fix it.

• Step 1: Cold Start Procedure:

  • Engage the Choke: For a cold start, engage the choke fully. On most Stihl chainsaws, this involves moving the choke lever to the uppermost position.
  • Pull the Starter Cord: Pull the starter cord until the engine “pops” or briefly fires. This usually takes 2-3 pulls.
  • Disengage the Choke: Immediately disengage the choke one notch (half-choke position).
  • Pull Again: Pull the starter cord until the engine starts and runs.
  • Warm-Up: Allow the engine to warm up for a few seconds before applying full throttle.

• Step 2: Warm Start Procedure:

  • No Choke: For a warm start, do not engage the choke.
  • Pull the Starter Cord: Pull the starter cord until the engine starts.

• Step 3: Avoid Over-Choking: Be careful not to over-choke the engine, especially when it’s already warm.

• Step 4: Use Fresh Fuel: Use fresh, high-quality fuel with the correct oil mixture (typically 50:1 for Stihl chainsaws). Stale fuel can cause starting problems and flooding.

• Step 5: Store the Chainsaw Properly: Store the chainsaw in a dry place with the fuel tank empty or stabilized with a fuel stabilizer.

Personal Experience: I’ve learned the importance of proper starting technique through trial and error. In my early days of using chainsaws, I frequently flooded them by over-choking. By following the correct starting procedure, I’ve significantly reduced the incidence of flooding.

Data and Insights: Proper starting technique can significantly reduce the risk of flooding and extend the life of your chainsaw. Using fresh fuel and storing the chainsaw properly are also essential for preventing starting problems.

Fuel and Oil Specifications:

• Fuel: Use unleaded gasoline with a minimum octane rating of 89.
• Oil: Use Stihl 2-stroke engine oil or a high-quality synthetic 2-stroke oil.
• Fuel Mixture: Mix the fuel and oil at a ratio of 50:1 (2.6 ounces of oil per gallon of gasoline).
• Fuel Stabilizer: Add a fuel stabilizer to the fuel if you plan to store the chainsaw for more than a month.

Additional Considerations:

• Carburetor Problems: If your chainsaw continues to flood despite trying these methods, there may be an underlying problem with the carburetor. Common carburetor problems include a stuck needle valve, a clogged fuel filter, or a damaged diaphragm. In these cases, it’s best to take the chainsaw to a qualified repair technician.
• Compression: Low compression can also cause starting problems. If your chainsaw is difficult to start and lacks power, have the compression checked by a technician.
• Altitude: Altitude can affect the fuel mixture. If you’re using your chainsaw at high altitudes, you may need to adjust the carburetor to lean out the fuel mixture.
• Wood Type: The type of wood you’re cutting can also affect engine performance. Cutting hardwoods like oak or maple requires more power than cutting softwoods like pine or fir. Ensure your chainsaw is properly tuned for the type of wood you’re cutting.

Case Study: Reviving a Neglected Stihl 029

I once purchased a used Stihl 029 from a local estate sale. It had been sitting in a shed for several years and was in rough condition. The engine was completely flooded, and the fuel tank was full of stale fuel.

Here’s how I revived it:

1. Drained the Fuel Tank: I drained the old fuel from the fuel tank and replaced it with fresh fuel mixed with a fuel stabilizer.
2. Removed and Cleaned the Spark Plug: The spark plug was heavily fouled with carbon. I cleaned it thoroughly with a wire brush and checked the gap.
3. Used the “Air It Out” Method: I removed the spark plug, turned the saw upside down, and pulled the starter cord repeatedly to expel the excess fuel from the cylinder.
4. Cleaned the Air Filter: The air filter was clogged with dirt and debris. I cleaned it with soap and water and allowed it to dry completely.
5. Inspected the Fuel Filter: The fuel filter was also clogged. I replaced it with a new one.
6. Tried Starting the Saw: After reassembling everything, I tried starting the saw using the normal starting procedure. It took several pulls, but eventually, the engine sputtered to life.
7. Adjusted the Carburetor: The engine was running rough, so I adjusted the carburetor screws to fine-tune the fuel mixture.
8. Let it Run: I let the saw run for about 15 minutes to allow the engine to warm up and the carburetor to adjust properly.

After this process, the Stihl 029 ran like new. It was a testament to the durability of Stihl chainsaws and the effectiveness of these troubleshooting techniques.

Strategic Insights:

• Regular Maintenance: Regular maintenance is crucial for preventing starting problems and extending the life of your chainsaw. This includes cleaning the air filter, replacing the fuel filter, and inspecting the spark plug regularly.
• Use Quality Fuel and Oil: Using high-quality fuel and oil is essential for optimal engine performance and longevity. Avoid using stale fuel or low-quality oil.
• Store Your Chainsaw Properly: Storing your chainsaw properly when it’s not in use can prevent starting problems and other issues. Empty the fuel tank or add a fuel stabilizer before storing the saw for an extended period.
• Know Your Chainsaw: Familiarize yourself with the specific features and operating procedures of your chainsaw model. Consult the owner’s manual for detailed instructions.
• Safety First: Always prioritize safety when working with chainsaws. Wear appropriate safety gear, including eye protection, hearing protection, gloves, and chainsaw chaps.

Next Steps:

Now that you’ve learned these five pro tips for starting a flooded Stihl chainsaw, it’s time to put them into practice.

1. Familiarize Yourself with Your Chainsaw: Take the time to read your chainsaw’s owner’s manual and understand its specific features and operating procedures.
2. Practice the Starting Procedure: Practice the cold start and warm start procedures until you’re comfortable with them.
3. Gather Your Tools: Assemble the necessary tools for troubleshooting starting problems, including a spark plug wrench, a spark plug gapping tool, a wire brush, and a carburetor adjustment screwdriver.
4. Inspect Your Chainsaw Regularly: Make it a habit to inspect your chainsaw regularly for signs of wear and tear or potential problems.
5. Don’t Be Afraid to Seek Help: If you’re unable to resolve a starting problem on your own, don’t hesitate to take your chainsaw to a qualified repair technician.

By following these steps, you can keep your Stihl chainsaw running smoothly and efficiently for years to come.

Remember, chainsaws are powerful tools that require respect and careful handling. Always prioritize safety and follow the manufacturer’s instructions. With the right knowledge and techniques, you can tackle even the most challenging chainsaw problems and keep your wood processing projects on track.

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