How to test small engine ignition coil without multimeter? Latest {In-2023}

Small engines are found in various equipment such as lawnmowers, chainsaws, and generators. The ignition coil is a critical component that ensures the engine starts and runs smoothly. If you suspect a faulty ignition coil, it’s essential to test it to diagnose the issue accurately. While using a multimeter is the most common method, there are alternative ways to test a small engine ignition coil without one.

Signs of a Faulty Ignition Coil

The ability to identify the symptoms of a damaged ignition coil is essential for effective troubleshooting. Engine misfires, difficulty starting the engine, stalling, and a notable loss in engine performance are all symptoms of a faulty coil. By recognizing these signs, you can determine if the ignition coil requires testing.

How to test small engine ignition coil without multimeter?

How to test small engine ignition coil without multimeter

If a multimeter is not available, there are other ways to test a small engine ignition coil. Visual inspection is one such method, where you carefully examine the coil for visible signs of damage or wear. Additionally, testing the spark plugs can provide insights into the coil’s condition.

Step#1: Visual Inspection

  • Check for physical damage such as cracks, dents, or melted insulation on the ignition coil.
  • Examine the coil for any signs of corrosion, rust, or moisture accumulation.
  • Look for loose connections or frayed wires that may affect the coil’s performance.
  • Inspect the coil for any oil or fluid leaks, which can indicate a potential issue.
  • Check the coil’s mounting brackets or screws for stability and tightness.
  • Look for any visible signs of overheating, such as discoloration or burnt marks.
  • Pay attention to the overall condition of the coil, ensuring it appears clean and well-maintained.
  • Take note of any unusual or abnormal physical characteristics that may indicate a faulty coil.

Step#2: Checking Spark Plugs

  • Remove each spark plug from the engine using a spark plug socket and ratchet.
  • Inspect the spark plug’s electrode for signs of fouling, such as carbon buildup or oil deposits.
  • Look for any damage to the spark plug, such as cracks, chips, or worn-out electrodes.
  • Check the spark plug’s gap using a feeler gauge to ensure it meets the manufacturer’s specifications.
  • Examine the color of the spark plug’s ceramic insulator. A light tan or gray color indicates a healthy combustion process, while black, white, or uneven deposits may indicate ignition coil issues.
  • Compare the condition of all the spark plugs. If one spark plug appears significantly different from the others, it may point to a specific cylinder or ignition coil problem.
  • Clean the spark plugs using a wire brush or spark plug cleaner if necessary, taking care not to damage the electrode.
  • Replace any damaged or faulty spark plugs with new ones, ensuring they are properly gapped before installation.

Remember, this outline provides an overview, and in the actual article, each bullet point will be expanded into a detailed paragraph, providing step-by-step instructions and explanations on checking spark plugs for small engine ignition coils.

Step#3: Testing Primary and Secondary Coils

Ignition coils have primary and secondary windings, each serving different functions. Testing these coils individually allows for a more precise diagnosis.

  • Disconnect the ignition coil from the spark plug wire and remove any other electrical connections.
  • Use a multimeter set to the resistance (ohms) mode to measure the primary coil resistance.
  • Place the multimeter probes on the positive and negative terminals of the primary coil.
  • Compare the measured resistance value with the manufacturer’s specifications. A significant deviation may indicate a faulty primary coil.
  • Perform a spark plug test to assess the functionality of the secondary coil.
  • Reconnect the ignition coil to the spark plug wire and ground the spark plug against the engine block.
  • Crank the engine or pull the starter cord to observe the spark at the spark plug tip.
  • Ensure the spark appears strong and consistent. A weak or intermittent spark may suggest a problem with the secondary coil.
  • Compare the spark intensity and consistency across all cylinders or ignition coils for consistency.
  • Take note of any abnormal readings or inconsistencies, as they may indicate issues with either the primary or secondary coil.

Step#4: Interpreting Test Results

Once you’ve completed the tests, you must analyse the results to determine whether the ignition coil is faulty

  1. For the primary coil resistance test, compare the measured resistance value with the manufacturer’s specified range. A reading within the specified range indicates a healthy primary coil, while a reading outside the range may suggest a faulty primary coil.
  2. When analyzing the spark plug test results, observe the spark’s intensity and consistency. A strong and consistent spark indicates a well-functioning secondary coil, while a weak or intermittent spark may point to a problem with the secondary coil.
  3. Consider the appearance of the spark plug’s ceramic insulator. A light tan or gray color suggests a healthy combustion process and indicates proper ignition coil functioning. However, if the insulator shows black, white, or uneven deposits, it may indicate ignition coil issues that need further investigation.
  4. Compare the test results across all cylinders or ignition coils. Consistency is key. If one cylinder or coil shows significantly different readings or spark behavior compared to the others, it may indicate a specific problem with that particular component.
  5. •Take into account any abnormal readings or inconsistencies observed during the tests. These anomalies may require additional diagnostics or further examination to pinpoint the exact issue with the ignition coil.
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Replacing a Faulty Ignition Coil

  • Gather the necessary tools and replacement ignition coil compatible with your small engine.
  • Ensure the engine is cool and disconnect the spark plug wire from the old ignition coil.
  • Locate the old ignition coil on the engine, usually near the spark plugs.
  • Depending on the model, you may need to remove any covers or components obstructing access to the ignition coil.
  • Carefully disconnect the electrical connectors and wires connected to the old ignition coil.
  • Remove any mounting bolts or screws securing the old ignition coil in place.
  • Take note of the position and orientation of the old ignition coil for reference during installation.
  • Safely remove the old ignition coil from the engine, taking care not to damage any surrounding components.
  • Prepare the new ignition coil for installation by ensuring it matches the specifications of your small engine and has the same connectors.
  • Position the new ignition coil in the same orientation as the old one, aligning it properly with the mounting holes.
  • Secure the new ignition coil in place using the appropriate mounting bolts or screws, ensuring a snug fit.
  • Reconnect the electrical connectors and wires to the new ignition coil, ensuring they are properly seated and secure.
  • If applicable, reinstall any covers or components that were removed to access the ignition coil.
  • Reconnect the spark plug wire to the new ignition coil.
  • Double-check all connections and ensure everything is properly tightened and secure.
  • Start the engine and observe its operation to ensure the new ignition coil is functioning correctly.
  • If the engine runs smoothly without any issues, the replacement of the faulty ignition coil was successful.

Maintenance Tips for Ignition Coils

  • Keep the ignition coil clean by regularly inspecting it for dirt, debris, or other contaminants. Use a soft cloth or brush to gently clean the exterior surface of the coil.
  • Check the ignition coil for proper grounding. Ensure that the coil’s mounting bracket or grounding wire is securely connected to a clean and solid ground point on the engine or chassis.
  • Inspect the spark plug wires and connectors for any signs of damage, such as cracks, fraying, or corrosion. Replace any faulty wires or connectors to ensure a reliable connection between the ignition coil and spark plugs.
  • Regularly inspect related components, such as the distributor cap or ignition module, for wear or damage. Replace any worn or faulty parts to maintain optimal ignition system performance.
  • Ensure that the ignition coil is securely mounted in its designated location. Loose or improperly secured coils can cause vibrations, which may lead to premature wear or damage.
  • Follow the manufacturer’s recommended maintenance schedule for your specific small engine. This may include periodic inspection and replacement of ignition components, including the ignition coil.
  • Avoid excessive heat exposure to the ignition coil. Keep it away from high-temperature areas of the engine to prevent overheating, which can degrade its performance.
  • If you notice any symptoms of ignition coil failure, such as misfires, rough idle, or difficulty starting the engine, address the issue promptly. Ignoring these signs can lead to further damage to the ignition system.
  • Consider using dielectric grease on the spark plug connectors to prevent moisture or corrosion. Apply a small amount of grease to the inside of the connector before reattaching it to the ignition coil.
  • Periodically check the ignition coil’s wiring harness for any signs of wear or damage. Ensure that the wires are properly insulated and free from any exposed areas that may cause electrical issues.

Safety Precautions

Before working on the ignition coil or any electrical components, ensure that the engine is turned off and has cooled down to avoid the risk of burns or other injuries.

  • Disconnect the power source or remove the spark plug wire from the ignition coil to prevent accidental engine starts while working on it.
  • Wear appropriate protective gear, including safety goggles or glasses, gloves, and protective clothing, to safeguard against any potential hazards or electrical shocks.
  • Take caution when handling ignition coils, as they can generate high voltages. Avoid touching the metal contacts or terminals of the coil to minimize the risk of electrical shock.
  • When removing or installing ignition coils, be mindful of the surrounding components and avoid damaging any other parts or wires.
  • If you suspect an issue with the ignition coil or the electrical system, it is recommended to consult a professional mechanic or technician for assistance, especially if you are not experienced with small engine repairs.
  • Follow the manufacturer’s guidelines and instructions provided in the engine’s manual when working on the ignition coil or any other components of the ignition system.
  • Avoid working on the ignition system in wet or damp conditions to minimize the risk of electrical shock or damage to the components.
  • Store ignition coils and other electrical components in a dry and safe location to prevent exposure to moisture or corrosive elements.
  • Dispose of old or faulty ignition coils according to local regulations and guidelines to ensure proper handling and environmental safety.


Testing small engine ignition coils without a multimeter is possible using alternative methods such as visual inspection and spark plug examination. While a multimeter offers the most precise measurements, these alternative methods can provide valuable insights into the condition of the coil. Remember to prioritize safety when working with electrical components and consult a professional if needed.

Frequently Asked Questions (FAQ’s)

Can I test an ignition coil without any tools?

While it’s recommended to use tools for accurate testing, visual inspection and spark plug examination can provide initial indications of coil health.

How often should I test my small engine ignition coil?

Testing the ignition coil during routine maintenance or if you suspect a problem is a good practice. However, follow the manufacturer’s recommendations for specific intervals.

Can a faulty ignition coil damage other engine components?

Yes, a faulty ignition coil can lead to misfires and irregular combustion, which may cause damage to spark plugs, valves, and other engine parts over time.

Are ignition coils interchangeable between different small engines?

Not necessarily. Ignition coils have specific compatibility requirements, so it’s important to match the coil with the engine’s make and model.

Is it possible to repair a faulty ignition coil?

Generally, ignition coils are not repairable and should be replaced if diagnosed as faulty. Attempting repairs may compromise their performance and reliability.