The roar of a lawnmower is a familiar sound of summer. But what happens when that familiar roar turns into a sputtering cough? One common culprit for a lawn mower that won’t start is a faulty ignition coil. This vital component plays a crucial role in generating the spark that ignites the fuel-air mixture, bringing your mower to life. If your mower is giving you trouble, this article will equip you with the knowledge to diagnose a bad ignition coil and guide you through the steps to test it yourself. We’ll cover the basics of how ignition coils work, the signs of a failing coil, the tools you’ll need, and the step-by-step process for testing the coil.
Understanding the Role of an Ignition Coil
An ignition coil is a crucial part of your lawn mower’s ignition system. Its job is to transform low-voltage electricity from the battery into a high-voltage spark that travels to the spark plugs, igniting the fuel-air mixture within the cylinders. This spark is what ultimately powers your mower. A malfunctioning ignition coil can cause a variety of issues, leading to a frustrating and inconvenient mowing experience.
Identifying the Symptoms of a Failing Ignition Coil
Before diving into testing, it’s essential to recognize the telltale signs of a faulty ignition coil. These symptoms can help you pinpoint the issue and avoid unnecessary troubleshooting.
Common Symptoms of a Bad Ignition Coil:
- No spark: This is the most obvious symptom. If you’re not getting any spark at the spark plugs, the ignition coil is likely the culprit.
- Mower starts, but dies quickly: The coil might be producing a weak spark, enough to start the engine but not sustain it.
- Engine runs poorly: A failing coil can cause the engine to run erratically, misfire, or sputter.
- Backfiring: If the spark is mistimed, it can cause a backfire, potentially damaging the engine.
If you experience any of these symptoms, it’s time to investigate your ignition coil.
Testing the Ignition Coil: A Step-by-Step Guide
Once you suspect your ignition coil is the issue, it’s time to test it. This procedure is relatively simple and requires only a few basic tools.
You’ll need:
- A multimeter: A multimeter is essential for checking for continuity and voltage.
- Spark plug wrench: You’ll need this to remove the spark plug for testing.
- A screwdriver: Used for removing the ignition coil wires.
- Wire brushes: To clean the terminals and ensure good contact.
Here’s how to test the ignition coil:
1. Disconnect the Ignition Coil
- Locate the ignition coil: The ignition coil is typically located near the spark plug(s) on your lawn mower. It is usually a small, cylindrical component with wires connected to it.
- Disconnect the wires: Carefully disconnect the wires leading to the ignition coil and the spark plug(s).
2. Inspect the Ignition Coil
- Visual inspection: Look for any signs of damage, cracks, or corrosion on the coil itself.
- Check for loose or damaged wires: Ensure the wires are securely connected and free from any damage.
3. Check for Continuity
- Set your multimeter to the ohms setting: Most multimeters have a setting that measures resistance, denoted by the symbol “Ω”.
- Connect the multimeter probes to the coil’s terminals: Consult your mower’s manual to determine which terminals are for the primary and secondary windings.
- Read the resistance: If the reading is within the range specified by your mower’s manual, the coil is likely in good working order. If the resistance is outside the specified range or you get an “OL” (open-loop) reading, the coil is likely faulty.
4. Test for Spark
- Remove the spark plug: Use the spark plug wrench to remove the spark plug from the engine.
- Attach the spark plug to the ignition coil wire: Make sure the wire is securely connected.
- Ground the spark plug: Hold the spark plug against a grounded metal surface, such as the engine block.
- Start the engine: Attempt to start the engine while observing the spark plug. If you see a strong blue spark, the coil is functioning correctly.
5. Repeat for Each Coil (If Applicable)
If your lawnmower has multiple ignition coils, repeat the above steps for each coil to ensure all are working properly.
6. Replace the Ignition Coil (If Necessary)
If your tests reveal a faulty ignition coil, it’s time to replace it.
- Find a compatible coil: Ensure the replacement coil is the correct one for your mower model. Refer to your mower’s manual or consult with a local auto parts store.
- Disconnect the old coil: Disconnect the old coil wires.
- Connect the new coil: Connect the new coil wires to the appropriate terminals.
- Reinstall the spark plug: Ensure the spark plug is securely installed.
Additional Troubleshooting Tips
- Check your battery: A weak battery can also cause starting problems.
- Inspect the spark plugs: Worn-out or fouled spark plugs can hinder spark and affect starting.
- Inspect the fuel system: Ensure the fuel line is not clogged, and the fuel filter is clean.
- Check the air filter: A dirty air filter can restrict airflow and affect combustion.
Remember: Before working on your lawnmower, always disconnect the battery to avoid electrical shocks.
Conclusion
Testing an ignition coil is a simple procedure that can save you time, money, and frustration. By understanding the symptoms of a faulty coil, learning the basic steps of testing, and using the right tools, you can confidently diagnose the problem and get your lawnmower back in action. If you discover a faulty coil, replacing it is a straightforward repair that will ensure your lawnmower starts reliably and efficiently. If you’re not comfortable performing these tests yourself, always consult with a qualified mechanic for assistance.
FAQ
What is an ignition coil and what does it do?
An ignition coil is a crucial component in a lawnmower’s ignition system. It acts as a transformer that converts the low voltage (typically 12 volts) from the battery into a much higher voltage (thousands of volts). This high voltage is then delivered to the spark plugs, causing them to ignite the air-fuel mixture in the engine’s combustion chamber. In essence, the ignition coil is responsible for generating the spark that powers your lawnmower.
Without a properly functioning ignition coil, your lawnmower won’t start or will run erratically. If you suspect the coil is faulty, it’s essential to diagnose and replace it as soon as possible to ensure your lawnmower operates efficiently and safely.
What are the signs of a bad ignition coil?
Several signs indicate a failing ignition coil in your lawnmower. One of the most obvious is difficulty starting. The engine might crank but not fire, or it may start but run poorly. Another common symptom is misfiring, which causes the engine to sputter or run unevenly. You may also notice a decrease in power or a lack of acceleration. Finally, a burnt smell coming from the engine could signal an overheating ignition coil.
If you experience any of these symptoms, it’s important to inspect the ignition coil for signs of damage, such as cracks, burns, or corrosion. If you find any damage, the coil needs to be replaced to restore proper ignition function and prevent further damage to your lawnmower.
How do I test my lawnmower’s ignition coil?
Testing a lawnmower’s ignition coil requires a few basic tools and some knowledge of electrical circuits. First, you’ll need a multimeter and a spark plug tester. Disconnect the wire leading to the spark plug and use the spark plug tester to check for a spark. If there’s no spark, you’ll need to test the ignition coil.
With the multimeter, check the resistance across the primary and secondary windings of the coil. Refer to your lawnmower’s manual or a reliable online source for the specific resistance values for your model. If the resistance readings are significantly different from the specified values, the ignition coil is likely faulty and needs replacement.
Why is my ignition coil going bad?
Several factors can contribute to the failure of an ignition coil. The most common cause is wear and tear over time. As the coil ages, the internal components can degrade, leading to decreased performance and eventual failure. Exposure to extreme temperatures, moisture, and vibrations can also accelerate the deterioration of the coil.
Furthermore, faulty wiring or a malfunctioning battery can overload the ignition coil, causing it to overheat and burn out. In some cases, a clogged air filter or a fuel delivery problem can result in a lean fuel mixture, which can also stress the ignition coil and lead to failure.
What are the risks of running a lawnmower with a bad ignition coil?
Running a lawnmower with a bad ignition coil poses several risks. First and foremost, it can cause the engine to misfire or stall, making it difficult to operate the mower and potentially leading to accidents. A faulty coil can also lead to an overheating engine, potentially damaging other engine components or causing a fire.
Furthermore, a bad ignition coil can emit harmful emissions, contributing to air pollution. It’s crucial to address any ignition coil issues promptly to ensure the safe and efficient operation of your lawnmower while minimizing environmental impact.
How do I replace a bad ignition coil?
Replacing a bad ignition coil is a relatively straightforward process, but it requires some mechanical aptitude and familiarity with electrical systems. First, disconnect the battery to prevent accidental shocks. Then, locate the ignition coil, usually attached to the engine block near the spark plugs.
Disconnect the wire leads connected to the coil and carefully remove the mounting screws. Install the new coil in the same position, ensuring the wires are correctly connected. Finally, reconnect the battery and start the engine to test the new coil’s functionality.
Is it possible to repair a bad ignition coil?
In most cases, repairing a bad ignition coil is not possible or practical. The internal components, such as the windings and core, are typically damaged beyond repair. Attempting to repair a damaged coil can be dangerous and may not restore its functionality.
Therefore, if your ignition coil is faulty, it’s usually more cost-effective and safer to replace it with a new one. Replacing the coil ensures optimal performance and safety, preventing potential damage to other engine components and reducing the risk of accidents or malfunctions.