The warm sun is shining, the birds are singing, and you’re finally ready to tackle your overgrown lawn. You grab your trusty lawn mower, give it a pull, and… nothing. The engine coughs and sputters, then falls silent. Frustration sets in. What’s going on? Could it be the dreaded lawn mower coil?
This article will guide you through the process of testing your lawn mower coil, helping you diagnose the issue and get your mower back in action quickly. We’ll cover the basics of what a lawn mower coil does, how to identify a bad coil, and the steps involved in testing it. By the end, you’ll have the knowledge to tackle this common lawn mower problem like a pro.
What is a Lawn Mower Coil?
The ignition coil, often simply called a “coil,” is a crucial component in your lawn mower’s ignition system. It’s a small, cylindrical device that takes the low-voltage electrical signal from the ignition module and transforms it into a high-voltage spark that ignites the fuel-air mixture in the combustion chamber. This spark is essential for the engine to run.
Recognizing the Symptoms of a Bad Coil
A failing or faulty coil can cause a range of problems, leading to difficulties starting or running your mower. Here are some common signs that your lawn mower coil might be on the fritz:
- Engine won’t start: If the coil isn’t producing a strong spark, the engine won’t fire up at all.
- Engine runs erratically: A weak spark can cause the engine to sputter, misfire, or run inconsistently.
- Engine dies suddenly: A faulty coil can cause the engine to shut off abruptly, especially under load.
- Difficult starting: You might notice that your mower takes longer to start than usual, or requires multiple pulls.
How to Test a Lawn Mower Coil: A Step-by-Step Guide
Now, let’s get down to business and learn how to test your lawn mower coil. You’ll need a few basic tools:
- Multimeter: This essential tool measures voltage and resistance, allowing you to check the coil’s electrical characteristics.
- Spark plug wrench: This tool is used to remove and replace the spark plug.
- Spark plug tester: This device simulates the engine’s environment, allowing you to visually inspect the spark produced by the coil.
Step 1: Disconnect the Spark Plug Wire
Before you start testing, always disconnect the spark plug wire from the spark plug to prevent accidental shocks.
Step 2: Measure the Primary Resistance
Using your multimeter, set it to the resistance setting (usually symbolized by an ohm symbol). Locate the two terminals on the coil labeled “primary.” Touch the multimeter probes to these terminals and note the reading. The resistance value should be within the manufacturer’s specifications for your particular coil. If the reading is outside this range, the coil is likely faulty.
Step 3: Measure the Secondary Resistance
Next, you’ll test the secondary winding of the coil. Find the terminals labeled “secondary” (usually one terminal is connected to the high-voltage spark plug wire). Connect the multimeter probes to these terminals and record the resistance. Again, this value should be within the manufacturer’s specifications. A high or low resistance reading indicates a problem with the secondary winding.
Step 4: Check for Continuity
This step is crucial to determine if there are any internal breaks in the coil’s windings. Set your multimeter to the continuity setting. Touch one probe to the primary terminal and the other probe to the secondary terminal. The multimeter should indicate a continuous circuit, which means there are no breaks in the winding. If the meter shows an open circuit, the coil is defective.
Step 5: Test for Spark
For this step, you’ll need a spark plug tester. Connect the spark plug wire to the tester’s terminal and attach the tester to a grounded surface. With the engine off, turn the ignition key to the “ON” position. The spark plug tester should display a strong, blue spark. If there is no spark or the spark is weak, the coil is likely the culprit.
Troubleshooting Tips
- Check your connections: Ensure all connections to the coil, spark plug, and ignition module are secure and free of corrosion.
- Inspect the spark plug: A fouled spark plug can also cause starting problems. Clean or replace the spark plug if necessary.
- Check the ignition module: If the coil is good, the ignition module may be faulty. This component sends the signal to the coil to generate the spark.
Replacing the Lawn Mower Coil
If your tests confirm a faulty coil, it’s time to replace it. Here’s how:
- Identify the correct coil: Find the right coil for your specific lawn mower model. You can consult your owner’s manual or search online for the correct replacement part.
- Disconnect the old coil: Disconnect the spark plug wire and any other wiring connected to the old coil.
- Install the new coil: Connect the new coil to the existing wiring, making sure the connections are tight and secure.
- Reconnect the spark plug wire: Reattach the spark plug wire to the new coil.
- Test the engine: Start the engine and ensure it runs smoothly.
Preventative Maintenance Tips
While testing and replacing your coil is important when problems arise, preventative maintenance can extend the life of your coil and help avoid future issues.
- Regularly inspect the coil: Look for any signs of damage, cracks, or corrosion.
- Keep the coil clean: Dirt and debris can accumulate on the coil, affecting its performance.
- Avoid excessive vibration: Vibration can damage the coil’s internal components.
- Use high-quality spark plugs: Using worn-out or incorrect spark plugs can strain the coil and reduce its lifespan.
Conclusion
Testing a lawn mower coil may seem daunting at first, but with a little patience and the right tools, it’s a manageable task. By following the steps outlined in this guide, you can confidently diagnose a faulty coil and get your mower back in top shape. Remember, regular maintenance and careful inspection can help prevent coil issues and keep your lawn mower running smoothly for years to come.
Frequently Asked Questions
1. What is a lawn mower coil, and what does it do?
The ignition coil is a crucial component in your lawn mower’s engine. It acts like a transformer, taking low-voltage electricity from the battery and converting it into high-voltage electricity, which is then sent to the spark plugs. The spark plugs ignite the air-fuel mixture, making your engine run. Without a functional ignition coil, your lawn mower simply won’t start.
The coil consists of two main parts: the primary winding and the secondary winding. When the ignition system sends a signal to the coil, it creates a magnetic field in the primary winding. This magnetic field collapses and induces a high-voltage current in the secondary winding, which then travels to the spark plugs, creating a spark to ignite the fuel.
2. What are the signs that my lawn mower coil is failing?
Several signs can indicate a failing ignition coil. The most obvious is that your lawn mower won’t start at all. You might hear a clicking sound from the starter but no engine response. Other signs include difficulty starting the mower, the engine running intermittently, misfiring, or the engine dying randomly. If you notice any of these issues, it’s worth investigating your ignition coil as a potential culprit.
Additionally, if you observe the spark plugs and notice they are wet or have a black, sooty appearance, it could also be a sign of a failing coil. This suggests the coil is not delivering the necessary high-voltage current to the spark plugs, leading to incomplete combustion and the fuel buildup on the spark plugs.
3. How do I test my lawn mower coil?
Testing your lawn mower coil involves checking for continuity and resistance using a multimeter. The process is relatively straightforward and involves these steps:
First, disconnect the spark plug wires from the coil and the spark plugs. Then, set your multimeter to the ohms setting and probe the terminals on the coil. Compare your readings to the specifications provided in your lawn mower’s manual or online for your specific coil model. If the readings are significantly off, it indicates the coil is faulty and needs replacement.
However, if you are not comfortable working with electrical components or are unsure about the testing process, it’s always best to consult a qualified mechanic.
4. How do I replace my lawn mower coil?
Replacing a lawn mower coil is a relatively simple task. However, it does involve working with electrical components, so always exercise caution and disconnect the battery before starting the job. To replace the coil, you’ll need to locate it on the engine. It’s usually mounted near the spark plugs and connected to the ignition system.
Once you’ve located the coil, disconnect the wires leading to it, including the spark plug wires. Carefully remove the mounting screws holding the coil in place and pull it out. Now, install the new coil in the same position, ensuring the wires are connected correctly. Secure the coil with the mounting screws, reconnect the battery, and start your mower to test it.
5. Can I repair a faulty lawn mower coil?
While you can try to clean the contacts or terminals on the coil to improve connectivity, repairing a faulty ignition coil is generally not recommended. The coil is a sealed unit, and attempting to repair it can be dangerous and potentially damage other components in your engine.
If the coil is faulty, the best course of action is to replace it with a new one. You can find replacement coils at your local hardware store, auto parts store, or online retailers. Ensure you get a coil compatible with your specific lawn mower model.
6. How do I prevent my lawn mower coil from failing?
While coil failures can sometimes be unavoidable, there are steps you can take to prolong the life of your lawn mower coil. Regular maintenance is key. Ensure your battery is in good condition and fully charged, as a weak battery can strain the coil.
Also, keep the spark plugs clean and properly gapped. Finally, avoid using low-quality fuel, as it can lead to spark plug fouling and damage the coil.
7. What are the costs associated with replacing a lawn mower coil?
The cost of replacing a lawn mower coil can vary depending on the model and brand of your mower. Generally, a new coil can range from $20 to $100. If you have the skills and are comfortable working on your lawn mower yourself, you can save on labor costs.
However, if you choose to have a professional mechanic replace the coil, the cost can increase, depending on their labor rates. Remember, it is often cheaper to replace the coil rather than attempt to repair it, which can be time-consuming and may not be successful.