The dreaded sputtering, coughing, and refusal to start—sounds familiar? If your lawn mower isn’t firing up, the culprit might be a faulty ignition coil. This essential component plays a crucial role in generating the spark that ignites the fuel-air mixture, and a malfunctioning coil can leave you stranded in the middle of your lawn care duties. This article will guide you through the steps of testing your lawn mower coil, helping you diagnose the problem and determine if a replacement is needed.
In essence, testing a lawn mower coil involves verifying that it’s generating a strong enough spark to ignite the fuel. This can be done by using a basic multimeter or an ignition tester. By following a few simple steps, you can assess the health of your coil and potentially save yourself the cost of a mechanic visit.
Understanding the Ignition Coil: A Vital Component in Your Lawn Mower
The ignition coil is a critical component in your lawn mower’s ignition system. It acts as a transformer, converting low-voltage battery power into a high-voltage spark that ignites the fuel in the combustion chamber. This process is essential for starting and running your lawn mower smoothly.
How the Ignition Coil Works: A Simplified Explanation
When you turn the key, the battery sends a low-voltage current to the ignition coil. The coil’s primary winding, a coil of wire with many turns, stores this energy. When the points or electronic ignition system opens, the stored energy is transferred to the secondary winding, which has even more turns of wire. This process dramatically increases the voltage, generating a high-voltage spark that travels to the spark plug and ignites the fuel mixture.
Signs of a Faulty Ignition Coil:
Recognizing the symptoms of a faulty ignition coil can help you quickly diagnose the problem:
- Engine won’t start: This is the most common symptom. If your lawn mower doesn’t start or sputters inconsistently, a faulty coil could be the culprit.
- Backfiring: If your engine backfires, it could indicate that the ignition timing is off due to a malfunctioning coil.
- Engine misfires: A faulty coil can cause the engine to miss or run rough, leading to uneven power delivery.
- Spark plug isn’t firing: If you check the spark plug and it’s not producing a spark, the coil is likely the problem.
Testing the Ignition Coil: Two Proven Methods
Now that you understand the importance of the ignition coil, let’s dive into the testing methods. There are two popular ways to test your lawn mower coil:
1. Using a Multimeter: A Versatile Tool for Testing
A multimeter is a handy tool for diagnosing electrical problems, including checking the integrity of your ignition coil. It can measure resistance, voltage, and current, providing valuable insights into your coil’s performance.
1. Safety First: Disconnect the Battery
Before you start testing, always disconnect the battery from your lawn mower. This prevents accidental shocks and ensures a safe working environment.
2. Identify the Coil’s Terminals:
Most lawn mower coils have three terminals:
- Primary Terminal: This terminal connects to the battery and the ignition switch.
- Secondary Terminal: This terminal connects to the spark plug wire.
- Ground Terminal: This terminal provides a path for electrical current to flow back to the battery.
3. Measure Resistance:
- Primary Winding: Use the multimeter to measure the resistance between the primary terminal and the ground terminal. Refer to your lawn mower’s manual or the coil’s specifications to find the expected resistance value. If the measured resistance is significantly different, the coil might be faulty.
- Secondary Winding: Repeat the resistance measurement between the secondary terminal and the ground terminal. Again, compare the reading to the specified value to determine if the coil is working correctly.
4. Interpreting the Results:
- Open Circuit: If the multimeter reads “OL” (open circuit) or an extremely high resistance, the coil is faulty and needs replacement.
- Short Circuit: If the multimeter reads “0” (zero resistance), the coil has a short circuit and needs replacement.
- Correct Resistance: If the measured resistance values are close to the specifications, the coil is likely functioning properly.
2. Employing an Ignition Tester: A Direct Approach to Spark Detection
An ignition tester is a simple, dedicated tool designed to detect and visualize the spark generated by your ignition coil. It’s often the preferred method for testing a lawn mower coil, as it directly assesses the spark output.
1. Connect the Ignition Tester:
- Disconnect the battery to prevent electrical shocks.
- Remove the spark plug wire from the spark plug.
- Connect the ignition tester to the spark plug wire. Ensure a secure connection.
2. Crank the Engine:
- Turn the key to the “start” position. The ignition tester should light up if the coil is functioning correctly.
- Observe the Spark: Look for a bright, consistent spark jumping between the electrodes of the ignition tester.
3. Interpreting the Results:
- Strong, Consistent Spark: If the ignition tester produces a bright, consistent spark, the coil is working properly.
- Weak or No Spark: If the spark is weak, intermittent, or absent, the coil is likely faulty and needs replacement.
When to Replace Your Ignition Coil: Recognizing the Signs
If your tests reveal that your ignition coil is faulty, it’s crucial to replace it promptly to restore your lawn mower’s functionality. Here are some signs that indicate it’s time for a replacement:
- Consistent failed tests: If both multimeter and ignition tester tests point to a faulty coil, it’s time for a new one.
- Burning Smell: A burning smell coming from the coil area is a strong indicator of a coil failure.
- Physical Damage: If the coil shows signs of visible damage, such as cracks, burns, or loose connections, it needs to be replaced.
Replacing Your Lawn Mower Ignition Coil: A Step-by-Step Guide
Once you’ve determined that the coil is faulty, you can replace it with a new one. Here’s a step-by-step guide for a successful replacement:
- Disconnect the Battery: Always start by disconnecting the battery to ensure safety.
- Locate the Old Coil: Identify the ignition coil on your lawn mower. It’s usually located near the spark plug.
- Remove the Spark Plug Wire: Disconnect the spark plug wire from the coil’s secondary terminal.
- Remove the Coil’s Wires: Carefully disconnect any other wires connected to the coil.
- Remove the Coil: Release the coil’s mounting screws or clamps and remove the old coil.
- Install the New Coil: Position the new coil in the same location as the old one and secure it using the original mounting screws or clamps.
- Reconnect the Wires: Connect the spark plug wire to the new coil’s secondary terminal. Reconnect any other wires according to their original positions.
- Reconnect the Battery: Reconnect the battery.
- Test the Engine: Start your lawn mower and check if it runs smoothly. If the engine starts and runs without any issues, you’ve successfully replaced the coil.
Conclusion: Empowering Yourself to Diagnose and Fix Your Lawn Mower
Understanding how to test your lawn mower coil empowers you to diagnose and fix common engine problems yourself. By following the simple steps outlined in this guide, you can save time and money by avoiding unnecessary trips to the mechanic. Remember to prioritize safety, use the appropriate tools, and follow the recommended procedures for testing and replacement. With a little knowledge and effort, you can keep your lawn mower running smoothly and enjoy a well-maintained lawn.
Frequently Asked Questions
What is a lawn mower coil and what does it do?
The ignition coil is a vital component in your lawn mower’s ignition system. It’s responsible for transforming the low voltage from the battery into a high voltage that sparks the spark plug, igniting the fuel-air mixture in the engine cylinder. The coil acts as a transformer, boosting the voltage to a level high enough to create a spark that jumps the gap between the spark plug’s electrodes. Without a properly functioning coil, your lawn mower won’t be able to start or run.
How can I tell if my lawn mower coil is bad?
Several symptoms can indicate a bad ignition coil. One common sign is difficulty starting or a complete failure to start. If your lawn mower starts but runs rough or dies suddenly, a faulty coil could be the culprit. You might also notice misfiring, sputtering, or a lack of power. However, these symptoms could also stem from other issues, so it’s crucial to test the coil to confirm its condition.
How do I test a lawn mower coil?
Testing a lawn mower coil requires a multimeter and some basic knowledge of electrical circuits. First, disconnect the spark plug wire from the coil. Then, set your multimeter to the ohms setting and touch the probes to the coil’s terminals. Compare the reading to the coil’s specifications. If the resistance values are significantly off, your coil is likely bad.
Can I replace the ignition coil myself?
Replacing the ignition coil on a lawn mower is a relatively simple task that most DIY enthusiasts can handle. However, you’ll need a few basic tools, such as a wrench to loosen the coil’s mounting bolts and a screwdriver to remove any mounting screws. It’s also essential to ensure you’re using the correct replacement coil for your specific lawn mower model.
How much does a new ignition coil cost?
The cost of a new ignition coil varies depending on the make and model of your lawn mower. Typically, you can find replacement coils for between $20 and $50. However, it’s always advisable to check with your local auto parts store or online retailer for the most accurate pricing.
Can I test a lawn mower coil without a multimeter?
While using a multimeter is the most accurate method for testing a lawn mower coil, you can attempt a rudimentary test without one. Disconnect the spark plug wire from the coil and then hold the end of the wire about half an inch from a grounded metal object, like the engine block. If you see a spark when you crank the engine, the coil might be working. However, this method isn’t as reliable as using a multimeter.
What are some other causes of lawn mower starting problems?
While a bad ignition coil is a common cause for starting issues, other problems can prevent your lawn mower from firing up. These include a bad spark plug, a faulty fuel system (clogged fuel lines or filter), a low battery, or a blockage in the air filter. It’s crucial to eliminate these possibilities before concluding that the coil is the issue.