Coil For Stihl Chainsaw: Testing Tips (3 Pro Tricks)

Let’s dive into the heart of diagnosing a Stihl chainsaw’s ignition system. My expert tip? Before you even think about replacing the coil, check the air gap between the coil and the flywheel. Too wide, and you won’t get a strong enough spark. Too narrow, and you risk damaging the coil. It’s a simple check that can save you time, money, and a whole lot of frustration.

Coil for Stihl Chainsaw: Testing Tips (3 Pro Tricks)

I’ve spent a good chunk of my life around chainsaws, from felling trees in the Pacific Northwest to prepping firewood in the crisp air of the Adirondacks. And let me tell you, a reliable ignition system is the heartbeat of any chainsaw. A faulty coil can bring your entire operation to a screeching halt. That’s why I’m sharing three pro tricks for testing the coil on your Stihl chainsaw. These aren’t just theoretical; they’re born from years of troubleshooting in the field, often miles from the nearest repair shop.

Why Focus on the Coil?

The ignition coil is responsible for generating the high-voltage spark that ignites the fuel-air mixture in the cylinder. Without a properly functioning coil, your chainsaw simply won’t start or will run erratically. Replacing parts blindly can get expensive real fast, and it’s a waste of time. That’s why testing is crucial. According to Stihl’s official service manuals, a significant percentage of “no-start” issues are directly linked to ignition system malfunctions, often stemming from a faulty coil or improper air gap.

Pro Trick #1: The Visual Inspection – More Than Meets the Eye

This might seem basic, but never underestimate the power of a good visual inspection. Before you grab your multimeter, give the coil a thorough once-over.

Check for Cracks and Damage: Look closely for any cracks, chips, or signs of physical damage to the coil body. Even a small crack can allow moisture to penetrate and short-circuit the coil.
Inspect the Wiring: Examine the wires leading to and from the coil. Are they frayed, cut, or corroded? Pay close attention to the connections at the spark plug and the coil itself. Corroded connections are a common culprit, especially in humid environments.
Look for Burn Marks: Burn marks are a telltale sign of overheating, indicating a potential short circuit or internal failure within the coil. I once worked on a saw where the coil looked fine at first glance, but upon closer inspection, I found a tiny burn mark on the underside. Replacing the coil solved the problem instantly.
Air Gap Check: As I mentioned in the introduction, the air gap is crucial. Stihl specifies a precise air gap, typically between 0.2mm and 0.4mm (0.008 and 0.016 inches). Use a feeler gauge to ensure the gap is within this range. Too wide, and the spark will be weak. Too narrow, and the flywheel can rub against the coil, damaging both. I always keep a set of feeler gauges in my toolkit, and I recommend you do the same.

Data Point: According to a study conducted by the Forest Equipment Research Institute of Canada (FERIC), preventative maintenance, including regular visual inspections, can reduce chainsaw downtime by up to 20%.

Pro Trick #2: The Spark Test – Seeing is Believing

The spark test is a simple but effective way to determine if the coil is producing a spark.

Remove the Spark Plug: Disconnect the spark plug wire and remove the spark plug from the cylinder.
Re-attach the Spark Plug: Reconnect the spark plug wire to the spark plug.
Ground the Spark Plug: Hold the spark plug against a metal part of the engine block, ensuring a good ground connection.
Pull the Starter Cord: Pull the starter cord firmly and observe the spark plug gap. You should see a strong, blue spark. A weak, yellow spark or no spark at all indicates a problem with the coil, wiring, or spark plug.

Important Safety Note: Be careful not to touch the spark plug while pulling the starter cord, as you could receive a shock. I always wear insulated gloves when performing this test.

Troubleshooting the Spark Test:

No Spark: If you see no spark, the coil is likely faulty. However, before condemning the coil, check the spark plug itself. A fouled or damaged spark plug can also prevent a spark. Try a new spark plug to rule out this possibility.
Weak Spark: A weak spark can be caused by a low battery (if your saw has electric start), a corroded connection, or a failing coil. Clean the connections and re-test. If the spark remains weak, the coil is likely the culprit.
Inconsistent Spark: An inconsistent spark can indicate a loose connection or an intermittent fault within the coil. Check all connections and wiring for damage.

Personal Story: I once spent hours troubleshooting a chainsaw that wouldn’t start, only to discover that the spark plug wire was loose. A simple push to reseat the wire solved the problem. It’s a reminder that sometimes the simplest solutions are the easiest to overlook.

Pro Trick #3: The Multimeter Test – Digging Deeper

For a more precise diagnosis, use a multimeter to test the coil’s resistance. This test will help you determine if the coil is internally shorted or open.

Set the Multimeter: Set your multimeter to the ohms (Ω) setting.
Disconnect the Coil: Disconnect the coil from the wiring harness.
Test the Primary Winding: Place one probe of the multimeter on the primary terminal (the terminal that connects to the ignition module) and the other probe on the engine ground. You should get a low resistance reading, typically between 2 and 5 ohms. Refer to your Stihl service manual for the specific resistance range for your model.
Test the Secondary Winding: Place one probe of the multimeter on the spark plug terminal and the other probe on the engine ground. You should get a higher resistance reading, typically between 2,000 and 10,000 ohms. Again, refer to your Stihl service manual for the specific resistance range.
Interpret the Results:
- Zero Resistance: A reading of zero ohms indicates a short circuit within the coil.
- Infinite Resistance: A reading of infinite ohms indicates an open circuit within the coil.
- Out-of-Range Resistance: If the resistance readings are significantly outside the specified range, the coil is likely faulty.

Data Point: According to a survey of chainsaw repair shops, approximately 70% of faulty ignition coils show resistance readings outside the manufacturer’s specified range.

Example: I was recently working on a Stihl MS271 chainsaw that was experiencing intermittent starting problems. The spark test showed a weak spark, and the multimeter test revealed that the secondary winding resistance was significantly lower than the specified range. Replacing the coil resolved the issue and restored the chainsaw to full working order.

Beyond the Coil: Other Ignition System Components

While the coil is a common source of ignition problems, it’s essential to consider other components as well.

Spark Plug: As mentioned earlier, a fouled or damaged spark plug can prevent a spark. Replace the spark plug regularly, following Stihl’s recommended maintenance schedule.
Spark Plug Wire: Inspect the spark plug wire for cracks, cuts, and corrosion. Replace the wire if it is damaged.
Ignition Module: The ignition module (also known as the control unit) is responsible for triggering the coil to produce a spark. A faulty ignition module can also cause ignition problems. Testing the ignition module typically requires specialized equipment and expertise.
Flywheel: The flywheel contains magnets that generate the electrical current that powers the ignition system. Ensure the flywheel is clean and free of debris. Check the magnets for damage or demagnetization.
Kill Switch: A faulty kill switch can prevent the chainsaw from starting. Test the kill switch with a multimeter to ensure it is functioning correctly.

Sustainable Timber Selection: A Responsible Approach

While troubleshooting your chainsaw is crucial, it’s equally important to consider the source of your timber. Sustainable timber selection is not just a trend; it’s a responsibility.

Choose Certified Wood: Look for wood that is certified by organizations like the Forest Stewardship Council (FSC). FSC certification ensures that the wood comes from responsibly managed forests.
Source Locally: Sourcing timber locally reduces transportation costs and carbon emissions. It also supports local economies.
Use Salvaged Wood: Consider using salvaged wood from construction sites, demolition projects, or fallen trees. Salvaged wood is a sustainable and often unique source of timber.
Avoid Illegal Logging: Be aware of the risks of illegal logging and avoid purchasing wood from questionable sources. Illegal logging contributes to deforestation, habitat loss, and climate change.

Data Point: According to the World Wildlife Fund (WWF), illegal logging accounts for up to 15% of global timber trade.

Workflow Optimization: From Harvest to Firewood

Efficient workflow is key to maximizing productivity and minimizing waste in wood processing and firewood preparation.

Planning the Harvest Schedule: Plan your harvest schedule carefully, taking into account factors such as weather conditions, timber availability, and drying time.
Log Handling Efficiency: Optimize your log handling processes to minimize manual labor and reduce the risk of injury. Use log splitters, skidding winches, and other tools to move logs efficiently. I recommend investing in a good quality log splitter; it will save you time and energy in the long run.
Log Stacking for Optimal Airflow: Stack logs in a way that promotes airflow, allowing them to dry quickly and evenly. Consider using a raised platform or pallets to keep the logs off the ground.
Drying Methods: Choose the drying method that best suits your needs and resources. Air drying is the most common method, but kiln drying can significantly reduce drying time.
Tool Sharpening Techniques: Keep your chainsaw chain sharp to improve cutting efficiency and reduce the risk of kickback. Learn how to sharpen your chain properly or take it to a professional sharpener. A sharp chain makes a world of difference.

Data Point: A study by the University of Maine found that properly air-dried firewood has a moisture content of 20% or less, which is ideal for efficient burning.

Minimizing Wood Waste: A Cost-Effective and Environmentally Friendly Approach

Minimizing wood waste is not only environmentally friendly, but it can also save you money.

Accurate Log Measurement: Measure logs accurately before cutting to minimize waste. Use a measuring tape or a log scale.
Strategic Cutting Techniques: Use strategic cutting techniques to maximize the yield of usable wood. Consider the grain direction and the presence of knots or defects.
Utilize Small Pieces: Don’t discard small pieces of wood. Use them for kindling, woodworking projects, or composting.
Consider Wood Chips: Wood chips can be used for landscaping, mulching, or as a fuel source for wood-burning stoves or furnaces.

Common Challenges and Solutions

Even with the best planning and preparation, you’re bound to encounter challenges in wood processing and firewood preparation.

Wet Wood: Wet wood is difficult to cut and burns poorly. Allow wood to dry thoroughly before burning.
Knots: Knots can make wood difficult to split and can weaken the wood. Use a log splitter with a high tonnage rating to split knotted wood.
Hardwood vs. Softwood: Hardwood is denser and burns longer than softwood. Choose the type of wood that best suits your needs.
Kickback: Chainsaw kickback is a dangerous phenomenon that can cause serious injury. Use proper cutting techniques and wear appropriate safety gear to minimize the risk of kickback.

Safety First: Always wear appropriate safety gear when operating a chainsaw, including eye protection, hearing protection, gloves, and sturdy boots.

Current Trends and Best Practices

The wood processing and firewood production industry is constantly evolving. Stay up-to-date on the latest trends and best practices to improve your efficiency and sustainability.

Electric Chainsaws: Electric chainsaws are becoming increasingly popular due to their low noise levels, ease of use, and reduced emissions.
Automated Log Splitters: Automated log splitters can significantly increase productivity and reduce manual labor.
Biomass Boilers: Biomass boilers use wood pellets or wood chips to generate heat and electricity.
Sustainable Forestry Practices: Sustainable forestry practices are becoming increasingly important as concerns about deforestation and climate change grow.

Global Perspective: Challenges Faced by Small Workshops and Independent Loggers

The challenges faced by small workshops and independent loggers vary depending on their location and resources.

Access to Equipment: Small workshops and independent loggers may have limited access to expensive equipment such as log splitters, skidding winches, and kilns.
Financing: Obtaining financing for equipment and operations can be difficult for small businesses.
Market Access: Accessing markets for their products can be a challenge for small workshops and independent loggers.
Regulations: Complying with environmental regulations and safety standards can be costly and time-consuming.

Conclusion: Takeaways and Next Steps

Testing your Stihl chainsaw coil is a critical step in diagnosing and resolving starting and running problems. By using the three pro tricks I’ve shared – the visual inspection, the spark test, and the multimeter test – you can quickly and accurately determine if the coil is faulty.

Remember, safety is paramount when working with chainsaws. Always wear appropriate safety gear and follow Stihl’s recommended operating procedures.

Next Steps:

Gather Your Tools: Assemble the necessary tools, including a feeler gauge, spark plug wrench, multimeter, and insulated gloves.
Perform a Visual Inspection: Carefully inspect the coil for cracks, damage, and burn marks. Check the wiring and air gap.
Conduct a Spark Test: Perform the spark test to determine if the coil is producing a spark.
Use a Multimeter: Use a multimeter to test the coil’s resistance.
Replace the Coil (if necessary): If the coil is faulty, replace it with a new Stihl OEM coil.
Consider Other Components: Don’t forget to check other ignition system components, such as the spark plug, spark plug wire, and ignition module.

By following these steps, you can keep your Stihl chainsaw running smoothly and efficiently for years to come. And remember, a little preventative maintenance goes a long way. Happy cutting!

Coil for Stihl Chainsaw: Testing Tips (3 Pro Tricks)