The roar of a lawn mower engine is a familiar sound of summer, signaling a well-maintained yard and a relaxing weekend. But what happens when that roar turns into a sputtering cough, or worse, a complete silence? One of the most common culprits behind a lawn mower’s woes is a faulty ignition coil. This vital component, responsible for delivering the spark that ignites the fuel, can wear out or malfunction over time.
This article will guide you through the process of checking your lawn mower coil, helping you determine if it’s the source of your engine trouble. We’ll cover the basics of coil function, how to identify common signs of a faulty coil, and provide step-by-step instructions on testing your coil with a multimeter. By the end, you’ll be equipped with the knowledge to diagnose your lawn mower’s spark issues and get back to mowing with confidence.
What is a Lawn Mower Coil and How Does it Work?
A lawn mower ignition coil is a crucial part of the ignition system. It acts as a transformer, converting low-voltage battery power into high-voltage electricity that creates a spark at the spark plug. This spark ignites the fuel-air mixture in the combustion chamber, driving the engine.
The coil typically consists of two windings: a primary winding and a secondary winding. When the ignition switch is turned on, current flows through the primary winding, creating a magnetic field. When the points or electronic ignition system breaks the circuit, the magnetic field collapses rapidly, inducing a high voltage current in the secondary winding. This high voltage current is then delivered to the spark plug, generating a spark that ignites the fuel.
Recognizing the Symptoms of a Faulty Coil
Before you start testing your lawn mower coil, it’s important to be familiar with the common signs that indicate a potential problem. Here are some telltale symptoms:
- Engine Won’t Start: The most obvious sign of a faulty coil is a complete inability to start the engine. If the coil isn’t generating a spark, the fuel won’t ignite, and the engine won’t fire up.
- Engine Sputters and Dies: An intermittent spark caused by a failing coil can lead to sputtering or uneven engine performance. This is often accompanied by backfiring or a general lack of power.
- Misfiring Engine: If the coil isn’t delivering a consistent spark, the engine may misfire, resulting in a rough idle, uneven acceleration, or a loss of power.
- Visible Spark Problems: In some cases, you might be able to visually detect issues with the spark plug. If the spark plug isn’t firing, or if the spark appears weak or inconsistent, it’s a strong indication of a faulty coil.
How to Test a Lawn Mower Coil with a Multimeter
Testing your lawn mower coil with a multimeter is a straightforward process that can help you diagnose the issue. Here’s a detailed guide:
Step 1: Disconnect the Spark Plug Wire
Before you start, make sure the ignition switch is turned off and the key is removed. Disconnect the spark plug wire from the spark plug to prevent accidental electric shock.
Step 2: Set Your Multimeter to Resistance Mode
Turn on your multimeter and set it to the resistance (OHMS) mode. Most multimeters have a range setting for resistance; select a range that will accommodate the resistance of your coil.
Step 3: Connect the Multimeter Leads to the Coil Terminals
Locate the coil terminals on your lawn mower coil. Typically, there will be two terminals: one for the primary winding and one for the secondary winding. Connect the red lead of your multimeter to one terminal and the black lead to the other terminal.
Step 4: Check the Resistance Readings
Take note of the resistance readings displayed on your multimeter.
- Primary Winding: The resistance of the primary winding should be between 0.5 and 2 ohms.
- Secondary Winding: The resistance of the secondary winding should be between 5,000 and 20,000 ohms.
Step 5: Analyze the Readings
If the resistance readings are within the specified range for both windings, your coil is likely in good working order. If the readings are outside the acceptable range, it indicates a problem with the coil and it may need to be replaced.
Troubleshooting Common Coil Issues
1. No Resistance Readings: If you get no resistance readings at all, it could indicate a completely broken coil or a loose connection. Double-check your wiring and connections, and ensure that the terminals are clean and free from corrosion.
2. Resistance Readings Out of Range: If the resistance readings fall outside the expected range, it suggests a problem with the coil’s internal windings. In this case, it’s recommended to replace the coil.
3. Coil is Very Hot: A coil that gets extremely hot during operation could be a sign of a short circuit or other internal issues. In this case, it’s best to replace the coil to prevent further damage.
Replacing a Faulty Lawn Mower Coil
If you’ve diagnosed a faulty coil, replacing it is a relatively straightforward process. Here’s a general guide:
- Identify the Correct Coil: Make sure you purchase a coil that’s compatible with your specific lawn mower model. You can find the correct replacement coil online or at your local auto parts store.
- Disconnect the Old Coil: Disconnect the spark plug wire and any other wiring connected to the old coil.
- Remove the Old Coil: Carefully remove the old coil from its mounting location.
- Install the New Coil: Position the new coil in its designated location and secure it with the mounting hardware.
- Reconnect the Wiring: Reconnect the spark plug wire and any other wiring to the new coil, making sure the connections are secure.
- Test the Engine: Turn on the ignition switch and start the engine. Ensure that the engine is running smoothly and the coil is functioning correctly.
Tips for Maintaining Your Lawn Mower Coil
While you can’t completely prevent coil failure, there are steps you can take to extend its lifespan:
- Keep it Clean: Regularly clean the coil and its surrounding area to remove dust, dirt, and debris that can interfere with its performance.
- Inspect for Damage: Inspect the coil for any signs of physical damage, such as cracks, burns, or corrosion.
- Use Quality Spark Plugs: Using high-quality spark plugs can help reduce wear and tear on the coil.
- Avoid Overheating: Allow the engine to cool down before storing your lawn mower, especially after prolonged use.
Conclusion:
A faulty ignition coil can quickly turn a simple lawn care task into a frustrating ordeal. By understanding the signs of a coil problem, learning how to test it, and taking steps to maintain it, you can keep your lawn mower running smoothly and efficiently. Armed with this knowledge, you’ll be well-equipped to tackle any spark-related issues and enjoy a trouble-free mowing experience.
FAQs
1. What is a lawn mower coil and why is it important?
The ignition coil is a vital component in your lawnmower’s ignition system. It transforms the low voltage from your battery into the high voltage needed to create a spark in the spark plug, which ignites the air-fuel mixture in the engine. Without a functioning ignition coil, your lawnmower won’t start or run properly.
You might encounter issues like weak sparks, misfires, or complete engine failure. Diagnosing a faulty coil is crucial for timely repairs to ensure your lawnmower operates efficiently and reliably.
2. How do I know if my lawn mower coil is dead?
There are a few signs that can indicate a dead lawnmower coil. These include:
- No spark at the spark plug: If your lawnmower doesn’t start and you can’t see a spark when you test the spark plug, the coil is likely the culprit.
- Weak spark: If the spark plug is sparking but the lawnmower is still struggling to start, the coil might not be producing enough voltage.
- Engine misfiring: This can happen if the coil is intermittently failing to produce a spark, causing the engine to run rough and inconsistently.
These symptoms point to a potential problem with the ignition coil. However, it’s always best to verify the problem with a multimeter test.
3. How can I test my lawn mower coil using a multimeter?
Testing your lawnmower coil with a multimeter is a straightforward process:
- Disconnect the spark plug wire from the coil.
- Set the multimeter to the ohms setting.
- Connect the multimeter leads to the coil terminals.
- Observe the reading on the multimeter. If the coil is good, the reading should be within a specific range provided by the manufacturer.
- If the reading is outside the specified range, it suggests a faulty coil.
Remember to consult your lawnmower’s manual for the specific ohm range for your coil.
4. Can I replace my lawn mower coil myself?
Replacing a lawn mower coil is a relatively easy DIY task for those with basic mechanical skills:
- Disconnect the spark plug wire and any other wires connected to the coil.
- Remove the mounting screws or clamps holding the coil in place.
- Remove the old coil and install the new coil in the same location, making sure all connections are secure.
- Reconnect the wires and reattach the spark plug wire.
Always consult your lawnmower manual for specific instructions and safety precautions.
5. How do I choose the right replacement coil for my lawn mower?
Selecting the correct replacement coil is crucial for ensuring proper functionality and compatibility with your lawnmower. Here are a few key considerations:
- Make and Model: Ensure the new coil is specifically designed for your lawnmower’s make and model.
- Coil Type: There are various types of coils, so confirm the type needed for your lawnmower (e.g., single-cylinder vs. multi-cylinder).
- Voltage and Resistance: Verify that the replacement coil’s voltage and resistance match the specifications of your existing coil.
By carefully matching these specifications, you can guarantee the replacement coil will function seamlessly with your lawnmower.
6. How much does a new lawn mower coil cost?
The cost of a new lawn mower coil varies depending on the make and model of your lawnmower and the brand of the coil. However, you can typically expect to pay between $20 and $50 for a replacement coil.
It’s usually more economical to replace a faulty coil than to attempt repairs. A new coil offers greater reliability and ensures a smooth and efficient operation of your lawnmower.
7. Can a bad spark plug cause a lawn mower coil to fail?
While a faulty spark plug can sometimes create an abnormal load on the ignition coil, it’s not a direct cause of coil failure. However, a faulty spark plug can contribute to the coil’s premature wear and tear.
It’s important to ensure your spark plug is in good condition, as it plays a crucial role in the ignition process. Replacing a faulty spark plug can help prevent further stress on the coil and improve its overall lifespan.