How to Test Chainsaw Ignition Coil | A Step-By-Step Guide

One of the most important parts of any chainsaw engine is the chainsaw ignition coil. The coil creates the necessary spark by converting the weak voltages by electromagnetic induction into strong ones. In contrast to a chainsaw’s rumbling sound, the ignition coil performs its work passively.

But an inoperable ignition coil prevents you from operating your tool effectively. Your being here indicates that your tool’s coil is not functioning correctly. You could also ask how to use a multimeter to test a chainsaw ignition coil.

To test the chainsaw coil using a multimeter, first, attach both the positive and negative ends of the chainsaw ignition coil to the positive and negative cords of the Multimeter. This will enable you to identify the resistance. 

Attach the positive and negative terminals of the chainsaw ignition coil to the positive and negative cords of the multimeter to test the chainsaw coil. You can determine the coil’s resistance in this manner. But remember to first check the chainsaw’s correct resistance, which may be found in the user’s manual!

Keep in mind that the chainsaw’s razor-sharp teeth will only cut effectively if its ignition coil is operating properly. A chainsaw is a machine just like any other.

How to Test a Chainsaw Ignition Coil with a Multimeter

The ignition coil is a crucial component in a chainsaw’s ignition system, responsible for generating the high voltage needed to create a spark at the spark plug. If your chainsaw is experiencing ignition issues, testing the ignition coil with a multimeter can help determine if it is functioning correctly. This detailed guide will walk you through the step-by-step process of testing a chainsaw ignition coil using a multimeter.

Note: Before starting the testing procedure, ensure you adhere to all safety precautions, including wearing protective gloves and eyewear and disconnecting the spark plug wire.

Tools Required

1. Multimeter: A digital multimeter capable of measuring resistance (ohms).
2. Protective gloves and eyewear.

Step 1: Prepare the Multimeter

Set your multimeter to the resistance (ohms) measurement mode. Ensure that the multimeter is properly functioning and has functional leads.

Step 2: Locate the Ignition Coil

Identify the ignition coil’s location on your chainsaw. It is generally positioned near the engine and connected to the spark plug wire. Refer to your chainsaw’s manual if necessary.

Step 3: Disconnect the Spark Plug Wire

To prevent accidental engine start-up during testing, carefully disconnect the spark plug wire from the spark plug. Ensure the wire is clear of the spark plug and any other metal parts.

Step 4: Locate the Coil’s Primary and Secondary Terminals

The ignition coil has two terminals—an outer terminal for the primary winding and an inner terminal for the secondary winding. Identify these terminals on the coil.

Step 5: Test the Primary Winding

The primary winding of the ignition coil is responsible for receiving power from the ignition module. Follow these steps to test it:

1. Connect the Multimeter’s Leads: Take the positive (red) lead of the multimeter and connect it to the coil’s outer terminal (primary winding). Take the negative (black) lead of the multimeter and connect it to a good ground, such as the chainsaw’s metal body.
2. Measure Resistance: With the multimeter leads in place, check the resistance reading displayed on the multimeter. Refer to your chainsaw’s manual for the specified resistance range, as it may vary depending on the model and manufacturer. Typically, a healthy ignition coil will have a resistance reading between 0.2 and 2 ohms. If the resistance is significantly higher or lower, it may indicate a problem with the primary winding.
3. Interpret the Results: If the resistance reading falls within the specified range, the primary winding is likely functioning correctly. If the resistance reading is infinite (∞) or shows no continuity, it indicates an open circuit in the primary winding, suggesting a faulty coil.

Step 6: Test the Secondary Winding

The secondary winding of the ignition coil produces the high voltage required for the spark plug. Proceed as follows to test it:

1. Reconnect the Multimeter’s Leads: Disconnect the multimeter leads from the primary winding and reconnect the positive (red) lead to the coil’s inner terminal (secondary winding). Keep the negative (black) lead connected to the good ground.
2. Measure Resistance: Similar to the primary winding test, measure the resistance of the secondary winding. The specified resistance range will vary depending on the chainsaw model. Typically, a healthy coil will display a resistance reading between 2,000 and 5,000 ohms. If the reading is significantly higher or lower, it may indicate a problem with the secondary winding.
3. Interpret the Results: If the resistance reading falls within the specified range, the secondary winding is likely functioning correctly. If the resistance reading is infinite (∞) or shows no continuity, it indicates an open circuit in the secondary winding, suggesting a faulty coil.

Testing the ignition coil of your chainsaw using a multimeter is a straightforward process that can help identify potential ignition system issues. By following the step-by-step instructions outlined in this guide, you can determine whether the ignition coil is functioning properly. Remember, if the coil fails any of the tests or you suspect a problem, it is advisable to consult a professional or replace the ignition coil to ensure optimal chainsaw performance and safety.

How to Test a Small Engine Ignition Coil Without a Multimeter

Testing a small engine ignition coil without a multimeter can be done using alternative methods to assess its functionality. Here’s a detailed guide on how to test a small engine ignition coil without a multimeter:

Note: Before proceeding, ensure you take appropriate safety precautions, including wearing protective gloves and eyewear. Also, disconnect the spark plug wire to prevent accidental engine start-up during testing.

Tools Required

1. Spare spark plug
2. Insulated pliers or a well-insulated screwdriver
3. Jumper wire or a piece of insulated wire

Step 1: Prepare for Testing

Make sure you have a spare spark plug that is compatible with your small engine. This will be used to assess whether the ignition coil is generating a spark. Additionally, have a pair of insulated pliers or a well-insulated screwdriver on hand for the testing process.

Step 2: Access the Ignition Coil

Locate the ignition coil in your small engine. It is usually positioned near the engine, and the spark plug wire is connected to it. Refer to your engine’s manual if needed.

Step 3: Remove the Spark Plug

Disconnect the spark plug wire from the spark plug, and remove the spark plug from the engine cylinder. This will prevent the engine from starting during the testing process.

Step 4: Connect the Spark Plug Wire

Reconnect the spark plug wire to the spark plug. Ensure it is properly seated and secured to the spark plug.

Step 5: Create a Ground Connection

Using insulated pliers or a well-insulated screwdriver, create a good ground connection by placing the metal part of the spark plug against a metal surface on the engine. Ensure the spark plug is in contact with the metal and remains isolated from any combustible materials.

Step 6: Perform a Visual Inspection

Visually inspect the ignition coil and its components. Look for any visible signs of damage, such as cracks, corrosion, or loose connections. If you observe any significant issues, the coil may need to be replaced.

Step 7: Test for Spark

This method involves observing the presence of a spark when attempting to start the engine. Follow these steps to perform the spark test:

1. Hold the spark plug’s threaded part with insulated pliers or insulated gloves.
2. Ground the spark plug by touching the metal part of the spark plug against the engine’s metal surface.
3. Have someone pull the engine’s starter rope or use an electric starter while you observe the spark plug.
4. Look for a visible spark between the spark plug’s electrodes. The spark should be strong and consistent.
5. If you do not see a spark or notice a weak spark, it suggests a problem with the ignition coil. It may be faulty and require replacement.
6. If you observe a strong and consistent spark, the ignition coil is likely functioning correctly.

Step 8: Repeat the Test

Repeat the spark test multiple times to ensure the consistency of the spark. Sometimes, an intermittent issue may cause the coil to produce a spark inconsistently.

While testing a small engine ignition coil without a multimeter may not provide precise resistance readings, the spark test can be a helpful alternative. By observing the presence and strength of the spark generated by the ignition coil, you can assess its functionality. If you do not see a spark or notice a weak spark, it indicates a potential issue with the coil. In such cases, consulting a professional or replacing the ignition coil is recommended to ensure the optimal performance of your small engine.

How to Test a Stihl Chainsaw Coil with a Multimeter

Note: Ensure you follow all safety precautions, such as wearing protective gloves and eyewear and disconnecting the spark plug wire.

Tools Required

1. Multimeter: A digital multimeter capable of measuring resistance (ohms).
2. Protective gloves and eyewear.

Step 1: Prepare the Multimeter

Set your multimeter to the resistance (ohms) measurement mode. Ensure that the multimeter is functioning correctly and the leads are in good condition.

Step 2: Locate the Ignition Coil

Find the ignition coil on your Stihl chainsaw. It is usually positioned near the engine and connected to the spark plug wire. Refer to your chainsaw’s manual if necessary.

Step 3: Disconnect the Spark Plug Wire

To prevent accidental engine start-up and ensure safety during testing, carefully disconnect the spark plug wire from the spark plug. Make sure the wire is clear of the spark plug and any other metal parts.

Step 4: Access the Coil Terminals

Identify the ignition coil’s primary and secondary terminals. The primary terminal is usually marked with an “S” or “SW” symbol, while the secondary terminal is marked with an “H” or “HT” symbol.

Step 5: Test the Primary Winding

The primary winding of the ignition coil receives power from the ignition module. Follow these steps to test it:

1. Connect the Multimeter’s Leads: Take the positive (red) lead of the multimeter and connect it to the primary terminal of the ignition coil. Take the negative (black) lead of the multimeter and connect it to a good ground, such as the chainsaw’s metal body.
2. Measure Resistance: With the multimeter leads properly connected, note the resistance reading displayed on the multimeter. Refer to your chainsaw’s manual for the specified resistance range for the primary winding. In general, a healthy Stihl chainsaw ignition coil will have a resistance reading between 0.2 and 2 ohms. If the resistance is significantly higher or lower, it may indicate a problem with the primary winding.
3. Interpret the Results: If the resistance reading falls within the specified range, the primary winding is likely functioning correctly. If the resistance reading is infinite (∞) or shows no continuity, it indicates an open circuit in the primary winding, suggesting a faulty coil.

Step 6: Test the Secondary Winding

The secondary winding of the ignition coil produces the high voltage required for the spark plug. Proceed as follows to test it:

1. Reconnect the Multimeter’s Leads: Disconnect the multimeter leads from the primary winding and reconnect the positive (red) lead to the secondary terminal of the ignition coil. Keep the negative (black) lead connected to the good ground.
2. Measure Resistance: Similar to the primary winding test, measure the resistance of the secondary winding. Again, refer to your chainsaw’s manual for the specified resistance range. Typically, a healthy coil will display a resistance reading between 2,000 and 5,000 ohms. If the reading is significantly higher or lower, it may indicate a problem with the secondary winding.
3. Interpret the Results: If the resistance reading falls within the specified range, the secondary winding is likely functioning correctly. If the resistance reading is infinite (∞) or shows no continuity, it indicates an open circuit in the secondary winding, suggesting a faulty coil.

By testing the ignition coil of your Stihl chainsaw using a multimeter, you can assess its primary and secondary windings for proper functionality. The resistance readings obtained during the testing process will help determine if the coil is in good condition or requires replacement. If you encounter any abnormalities or suspect a problem with the ignition coil, it is advisable to consult a professional or authorized Stihl service center for further assistance.

Chainsaw Ignition Coil Symptoms

The ignition coil is a critical component in a chainsaw’s ignition system. It converts the low voltage from the ignition module into high voltage, which is then delivered to the spark plug. If the ignition coil is faulty or experiencing issues, it can lead to various symptoms that affect the chainsaw’s performance. Here are some unique symptoms to look out for:

No Spark or Weak Spark

One of the most common signs of a faulty ignition coil is the absence of a spark or a weak spark at the spark plug. When you pull the starter rope or engage the electric starter, the engine may not start, or it may start but run poorly. A weak spark can cause misfires, rough idling, or difficulty starting the chainsaw.

Intermittent Starting Problems

If the ignition coil is damaged or malfunctioning, the chainsaw may exhibit intermittent starting problems. The engine may start and run fine on some occasions but fail to start or stall unexpectedly on other occasions. This inconsistency in starting can be a result of an unreliable spark from the faulty ignition coil.

Engine Stalling Under Load

A failing ignition coil can cause the engine to stall or cut out when the chainsaw is under load or at higher RPMs. The coil may struggle to generate the necessary high voltage, leading to a weak or intermittent spark. As a result, the engine may lose power and stall, particularly when cutting through dense or thick material.

Overheating

An overheating ignition coil can indicate an underlying problem. If the coil is not functioning efficiently or is experiencing electrical resistance issues, it can generate excessive heat. You may notice the ignition coil becoming excessively hot during operation, which can lead to performance issues and eventually cause the coil to fail completely.

Increased Fuel Consumption

A faulty ignition coil can disrupt the combustion process, leading to incomplete fuel burning and increased fuel consumption. The weakened or inconsistent spark can result in fuel not being fully ignited, causing the chainsaw to use more fuel than usual. If you notice a sudden decrease in fuel efficiency without any other apparent cause, the ignition coil could be a contributing factor.

Backfiring

In some cases, a faulty ignition coil can cause the engine to backfire during operation. Backfiring occurs when the fuel-air mixture in the cylinder ignites prematurely or in the exhaust system, resulting in loud popping noises. This symptom often arises from an irregular or weak spark that disrupts the combustion process.

The ignition coil plays a vital role in the proper functioning of a chainsaw’s ignition system. When it starts to exhibit symptoms such as no spark or weak spark, intermittent starting problems, engine stalling under load, overheating, increased fuel consumption, or backfiring, it indicates potential issues with the ignition coil. If you encounter any of these symptoms, it is recommended to have the chainsaw inspected and serviced by a qualified technician or authorized service center to diagnose and address the problem with the ignition coil effectively.

Working of Ignition Coils

The ignition coil in a chainsaw is a vital component of the ignition system, responsible for generating the high voltage needed to create a spark at the spark plug. It works through a process known as mutual induction, which involves the conversion of low voltage into high voltage.

Here’s a detailed explanation of how a chainsaw ignition coil works:

1. Primary Winding: The ignition coil consists of two windings, a primary winding, and a secondary winding. The primary winding consists of a few hundred turns of relatively thick wire and is connected to the ignition module or the magneto.
2. Low Voltage Input: When the engine is running, the ignition module sends a low-voltage electrical signal to the primary winding of the ignition coil. This low-voltage signal typically ranges from 12 to 48 volts.
3. Magnetic Field Generation: When the low voltage current flows through the primary winding, it creates a magnetic field around the coil. The magnetic field is produced because the current passing through the winding generates a magnetic flux.
4. Breaker Points or Transistors: In older chainsaws, the ignition system used breaker points to interrupt the primary circuit, creating a pulsating current flow and subsequently, a changing magnetic field. In modern chainsaws, electronic ignition systems utilize transistors to control the primary circuit.
5. Magnetic Field Collapse: When the primary circuit is interrupted, whether, through breaker points or a transistor, the current flow in the primary winding is suddenly cut off. This abrupt interruption causes the magnetic field in the coil to collapse rapidly.
6. High Voltage Induction: The collapsing magnetic field induces a high voltage, known as an electromotive force (EMF), in the secondary winding. The secondary winding consists of several thousand turns of much thinner wire than the primary winding.
7. High Voltage Output: The high voltage generated in the secondary winding of the ignition coil can reach several tens of thousands of volts, typically between 10,000 and 30,000 volts. This high voltage is then delivered to the spark plug through the spark plug wire.
8. Spark Creation: The high voltage from the ignition coil jumps across the spark plug’s electrodes, creating a spark. This spark ignites the air-fuel mixture in the chainsaw’s cylinder, enabling combustion and powering the engine.
9. Timing and Synchronization: The ignition module controls the timing and synchronization of the spark, ensuring it occurs at the right moment in the engine’s combustion cycle.
10. Repeat Cycle: The process of low voltage input, magnetic field generation, field collapse, high voltage induction, and spark creation is repeated continuously as long as the engine is running.

To Conclude, the chainsaw ignition coil works by converting the low voltage from the ignition module into a high voltage through mutual induction. The collapsing magnetic field in the primary winding induces a high voltage in the secondary winding, which is then used to generate a spark at the spark plug for combustion in the engine cylinder. This process is crucial for the chainsaw to run effectively and efficiently.

How to Test Chainsaw Ignition Coil – FAQs

To Wrap Up

To Wrap up, the ignition coil in a chainsaw plays a crucial role in generating the high voltage necessary for creating a spark at the spark plug. By converting low voltage through mutual induction, it creates a magnetic field that collapses rapidly, inducing a high voltage in the secondary winding.

Signs of a bad ignition coil include no spark or weak spark, intermittent starting problems, engine stalling, increased fuel consumption, overheating, and backfiring. Ignition coils can be damaged by factors such as electrical shorts, excessive heat, vibration, overvoltage, moisture or water ingress, and lack of proper maintenance. Regular inspection and maintenance of the ignition coil are important to ensure optimal performance and reliability of the chainsaw.