Imagine this: you’re ready to tackle your overgrown lawn, eager to restore its pristine glory. You pull the starter cord, but instead of the reassuring roar of the engine, you’re met with silence. The dreaded “won’t start” syndrome has struck again. Could it be a faulty ignition coil? This article will guide you through the process of testing your lawn mower coil, helping you pinpoint the issue and get your mower back in action. We’ll cover everything from understanding the coil’s role to performing simple tests, all while equipping you with the knowledge to diagnose and potentially troubleshoot your lawn mower woes.
Understanding the Ignition Coil
The ignition coil is a critical component in your lawn mower’s starting system. It’s responsible for transforming the low voltage from the battery into high voltage, which is then delivered to the spark plugs to ignite the fuel-air mixture. If the coil is faulty, it won’t generate the necessary high voltage, preventing the spark plugs from firing, ultimately leaving your mower unable to start.
How to Test a Lawn Mower Coil: A Step-by-Step Guide
Testing your lawn mower coil involves verifying its ability to produce a spark. You can achieve this using a few basic tools and a bit of technical know-how. Here’s a breakdown of the process:
1. Gather Your Supplies
Before you begin, make sure you have the following tools on hand:
- Multimeter: A digital multimeter is essential for testing the coil’s resistance and continuity.
- Spark plug tester: This device will allow you to visually check for a spark.
- Safety glasses and gloves: Always prioritize safety when working with electrical components.
2. Access the Ignition Coil
Locate the ignition coil on your lawn mower. It’s typically mounted near the spark plug, usually with a single wire connected to it.
3. Disconnect the Coil
Disconnect the wire leading from the ignition coil to the spark plug. This prevents any accidental shocks while testing.
4. Resistance Test (Primary Winding)
- Set your multimeter: Set the multimeter to the ohms (Ω) setting, typically a range appropriate for testing low resistance.
- Connect the probes: Touch the positive (red) probe to one terminal of the coil and the negative (black) probe to the other terminal.
- Check the reading: A healthy ignition coil will have a resistance reading within a specific range. Refer to your lawn mower’s manual or consult a reliable online resource for the specified resistance value.
5. Resistance Test (Secondary Winding)
- Locate the secondary terminals: The secondary winding is typically connected to a high-voltage wire that leads to the spark plug. Find the two terminals of the secondary winding.
- Repeat the resistance test: Use the same procedure as for the primary winding, but be prepared for a much higher resistance reading, typically in the kilohms (kΩ) range. Consult your manual or online sources for the correct resistance value.
6. Spark Test
- Connect the spark plug tester: Connect the spark plug tester to the high-voltage wire leading from the coil.
- Ground the spark plug tester: Ensure the ground clip of the spark plug tester is firmly connected to a good ground point on the engine block.
- Check for a spark: While someone else is cranking the engine, observe the spark plug tester. A healthy ignition coil will generate a strong blue spark.
7. Interpret the Results
- If the resistance tests show values within the specified range, and you observe a strong spark: Your ignition coil is likely functioning correctly. The problem may lie elsewhere in the starting system, such as a faulty spark plug or a broken wire.
- If the resistance tests reveal values outside the expected range, or you don’t see a spark: There’s a good chance your ignition coil is faulty and needs replacement.
Troubleshooting Additional Issues
Even if your ignition coil appears to be functioning correctly, you may still encounter problems starting your lawn mower. Here are a few other areas to investigate:
Faulty Spark Plug
- Visual inspection: Examine the spark plug for signs of damage, such as a cracked insulator or electrode wear.
- Spark plug gap check: Ensure the spark plug gap is set to the correct specification (refer to your manual).
- Spark plug test: Use a spark plug tester to check for a strong spark when connected to the spark plug wire.
Broken Wires
- Visual inspection: Look for any broken or frayed wires in the ignition system.
- Continuity test: Use a multimeter to test the continuity of all wires connecting to the ignition coil, spark plug, and other components.
Fuel System Issues
- Fuel level check: Ensure the fuel tank is adequately filled.
- Fuel filter check: Replace or clean a dirty fuel filter.
- Carburetor inspection: A clogged or dirty carburetor can hinder fuel flow and prevent starting.
Battery Issues
- Battery voltage check: Use a multimeter to verify the battery’s voltage. A fully charged battery should read around 12.6 volts.
- Battery terminals: Inspect the battery terminals for corrosion and clean them if necessary.
Replace the Ignition Coil (If Necessary)
If you’ve confirmed that your ignition coil is faulty, you’ll need to replace it with a new one.
Choosing the Right Replacement
- Compatibility: Ensure the replacement coil is compatible with your lawn mower model. Refer to the manufacturer’s specifications or consult a parts catalog.
- Quality: Invest in a high-quality ignition coil from a reputable brand.
Installation
- Disconnect the battery: Always disconnect the battery before working on the ignition system.
- Remove the old coil: Carefully disconnect the wires leading to the old coil and remove it from the mounting bracket.
- Install the new coil: Connect the wires to the new coil, ensuring they are securely fastened.
- Reconnect the battery: Reconnect the battery once the installation is complete.
Tips for Preventing Coil Problems
- Regular maintenance: Maintain a clean and well-ventilated engine compartment to prevent overheating of the ignition coil.
- Avoid prolonged cranking: Avoid excessively cranking the engine without starting, as this can overwork the coil.
- Quality fuel: Use high-quality fuel that is free from contaminants.
- Store properly: When storing your lawn mower for extended periods, ensure the fuel tank is empty or treated with a fuel stabilizer.
Conclusion
A faulty ignition coil can be a frustrating problem, leaving your lawn mower stranded. By understanding the coil’s role and mastering the simple tests outlined in this guide, you’ll be equipped to diagnose and potentially resolve this common issue. Remember to prioritize safety, consult your manual for specific instructions related to your model, and don’t hesitate to seek professional help if you’re unsure about any aspect of the process. With a little effort, you can get your lawn mower back in tip-top shape and conquer those overgrown patches with confidence!
FAQ
What is a lawn mower coil and what does it do?
The lawn mower coil is a vital component of your ignition system. It’s a small, cylindrical device that transforms low-voltage electrical current from the battery into a high-voltage spark that ignites the fuel in the engine’s combustion chamber. The coil is responsible for generating the spark that makes your lawn mower run, similar to how a car’s ignition system works.
Without a functioning coil, your lawn mower won’t start. The coil’s primary winding receives low voltage from the battery, which is then transferred to the secondary winding, increasing the voltage significantly. This high-voltage output goes to the spark plug, creating the spark that ignites the fuel-air mixture.
Why does my lawn mower coil go bad?
A few common reasons can lead to a faulty lawn mower coil. One is wear and tear due to prolonged use, heat, and vibration. The insulation on the coil wires can degrade over time, leading to short circuits or open circuits. Moisture and dirt can also damage the coil, causing corrosion and reducing its effectiveness.
Another factor is faulty spark plugs. If the spark plug is worn out or has a gap that is too wide, it can put excessive stress on the coil, potentially causing it to fail. Lastly, a bad battery can also contribute to coil failure by providing insufficient power for the ignition system, leading to excessive heat and strain on the coil.
How do I test my lawn mower coil?
Testing your lawn mower coil involves using a multimeter, a tool that measures electrical properties like voltage and resistance. First, disconnect the spark plug wire from the coil. Then, set the multimeter to resistance mode and touch the probes to the coil’s primary and secondary terminals.
Based on the coil’s specifications, the multimeter should display a specific resistance reading. If the reading is out of range or if the multimeter indicates an open circuit, your lawn mower coil is likely dead. If the resistance reading is within the specified range, the coil is likely in good condition.
What are the symptoms of a bad lawn mower coil?
A bad lawn mower coil can manifest in several ways. The most common symptom is a complete lack of spark, which will prevent the engine from starting. You might hear clicking or grinding sounds as the starter motor engages but fails to ignite the engine.
Another symptom could be intermittent starting issues, where the lawn mower occasionally fires up but then dies out. This can indicate a partially damaged coil that is only able to generate a spark intermittently. In extreme cases, a bad coil might lead to the engine running rough or misfiring, making it difficult to maintain a steady speed.
How do I replace my lawn mower coil?
Replacing a faulty lawn mower coil is a relatively straightforward task. First, locate the coil, which is typically attached to the engine block or near the spark plug. Disconnect the spark plug wire and the electrical wires connecting to the coil.
Then, using a wrench, loosen the mounting bolts securing the coil. After removing the old coil, carefully install the new one in its place, ensuring the wires are securely connected. Tighten the mounting bolts and reconnect the spark plug wire.
Can I use a coil from another lawn mower?
Using a coil from a different lawn mower might work, but it’s crucial to ensure compatibility. Coils are designed for specific engine models and may have different resistance values or terminal configurations.
If you’re unsure, consulting a service manual or contacting the manufacturer for compatibility information is recommended. Using an incompatible coil could potentially damage your ignition system, leading to further complications.
Can I repair a bad lawn mower coil?
Repairs are generally not possible for a dead lawn mower coil. The coil is a sealed unit, and internal components are not easily accessible. Attempts to repair the coil can be dangerous as it involves high voltage electricity.
If the coil is faulty, the best course of action is to replace it with a new one. Replacing the coil is a relatively inexpensive fix compared to the cost of potential engine damage caused by a faulty coil.