The frustration of a sputtering, refusing-to-start lawn mower is a familiar summer nightmare. While a multitude of issues could be at play, a faulty ignition coil is often the silent villain. This article will guide you through the process of testing your lawn mower’s ignition coil, allowing you to diagnose the problem and get your mower back in action. We’ll cover the basics of ignition coil function, the symptoms of a failing coil, and detailed step-by-step instructions for testing the coil with a multimeter. By the end, you’ll be equipped with the knowledge to confidently tackle this common lawn mower issue.
Understanding the Role of the Ignition Coil
The ignition coil plays a crucial role in igniting the fuel-air mixture in your lawn mower’s engine. It works by transforming the low voltage from the battery into a high-voltage spark that jumps across the spark plug gap, igniting the fuel.
Signs Your Lawn Mower Ignition Coil May Be Failing
A failing ignition coil can manifest in various ways, but some common signs include:
- Difficulty starting: The engine may sputter, crank slowly, or not start at all.
- Irregular running: The engine might run rough, miss, or cut out intermittently.
- No spark at the spark plug: This is the most definitive indicator of a faulty ignition coil.
Testing Your Ignition Coil: A Step-by-Step Guide
To test your lawn mower’s ignition coil, you’ll need a basic multimeter.
Step 1: Disconnect the Ignition Coil and Spark Plug
- Locate the ignition coil: The coil is usually mounted near the spark plug and often has a wire connected to the spark plug.
- Disconnect the spark plug wire: Gently pull the wire off the spark plug terminal.
- Disconnect the ignition coil wire: Unplug the wire that connects the ignition coil to the mower’s electrical system.
Step 2: Set Your Multimeter to Resistance Mode
- Select the ohms (Ω) setting: Your multimeter should have an ohms setting, typically represented by the symbol Ω.
- Choose an appropriate range: Start with a lower range like 200 ohms or 2k ohms.
Step 3: Test the Ignition Coil Primary Winding
- Touch the positive lead (red) of your multimeter to the ignition coil wire connector: This is the wire that was connected to the mower’s electrical system.
- Touch the negative lead (black) of your multimeter to the coil’s mounting bolt: Make sure the bolt is clean and free of corrosion.
- Read the resistance reading: Note the resistance value displayed on the multimeter.
Step 4: Test the Ignition Coil Secondary Winding
- Touch the positive lead (red) of your multimeter to the spark plug wire terminal: This is the terminal where the wire was attached to the spark plug.
- Touch the negative lead (black) of your multimeter to the coil’s mounting bolt: As before, ensure the bolt is clean.
- Read the resistance reading: Record the resistance value shown on your multimeter.
Step 5: Interpreting the Results
The specific resistance values you get will vary depending on the type and model of your lawn mower’s ignition coil. However, here are some general guidelines:
- Primary winding resistance: The resistance should be between 0.5 and 5 ohms.
- Secondary winding resistance: The resistance should be between 5,000 and 20,000 ohms.
If your readings fall outside these ranges, it is a strong indication that your ignition coil is faulty and needs to be replaced.
Troubleshooting Tips:
- Clean the connections: Corrosion can affect resistance readings. Clean the coil’s mounting bolt and the wire connectors with a wire brush.
- Double-check your connections: Ensure the multimeter probes are making good contact with the test points.
- Check your spark plug: A faulty spark plug can also cause similar symptoms. Replace the spark plug if necessary.
Conclusion:
Testing your lawn mower’s ignition coil is a simple, straightforward process that can help you pinpoint the source of your starting problems. By following the steps outlined above and understanding the resistance readings, you can quickly determine if the coil is the culprit. If you discover a faulty coil, replacing it is relatively inexpensive and will likely restore your mower to its former glory.
Frequently Asked Questions
What is an Ignition Coil?
An ignition coil is a vital component in your lawn mower’s engine that converts the low voltage from your battery into a high-voltage spark that ignites the fuel-air mixture in the combustion chamber. The coil acts as a transformer, boosting the voltage to thousands of volts, necessary for the spark plugs to fire properly. A faulty ignition coil can prevent your lawn mower from starting, cause misfires, or lead to inconsistent engine performance.
What are the Symptoms of a Bad Ignition Coil?
Several signs can indicate that your lawn mower’s ignition coil is failing. The most common is difficulty starting or a complete lack of ignition. You may also notice misfires, a sputtering engine, or a decrease in power. If you’re experiencing these issues, it’s essential to check the ignition coil to determine if it’s the source of the problem.
How do I Test the Ignition Coil?
To test your lawn mower’s ignition coil, you’ll need a multimeter. With the engine off, disconnect the spark plug wire from the coil and place the multimeter’s probes on the coil’s terminals. The multimeter should read a certain resistance, usually specified in the lawn mower’s manual. If the reading is outside the acceptable range, the coil is likely faulty.
Can I Replace the Ignition Coil Myself?
Replacing the ignition coil yourself is a relatively straightforward task that can be done with basic tools and a bit of mechanical know-how. You’ll need to locate the ignition coil, disconnect the wires leading to it, and then remove the old coil. Installing the new coil is simply the reverse process.
What Kind of Ignition Coil Should I Use?
When choosing a replacement ignition coil, ensure it’s compatible with your lawn mower’s make and model. The coil’s resistance, voltage, and other specifications should match the original coil. It’s best to consult your owner’s manual or a reputable parts supplier for the correct replacement coil.
How Often Should I Replace the Ignition Coil?
There’s no set schedule for replacing the ignition coil; it depends on factors like usage, maintenance, and environmental conditions. However, if your ignition coil is showing signs of wear or failure, it’s essential to replace it promptly to prevent further damage to the engine.
Can I Use a Universal Ignition Coil?
Universal ignition coils are designed to fit a wide range of lawn mowers, but they may not be the best choice for your specific model. While they can sometimes work, they may not provide the optimal performance or compatibility with your lawn mower’s specific electrical system. It’s generally best to stick with a coil specifically designed for your mower.