The satisfying hum of a lawnmower is a familiar sound of summer. But what happens when that hum turns into a frustrating silence? A common culprit for a non-starting lawnmower is a lack of spark. This article will guide you through the process of testing for spark, explaining the basics of how ignition systems work, and outlining the troubleshooting steps you need to take to get your mower back in action.
In essence, checking for spark involves testing if your lawnmower’s ignition system is generating a spark to ignite the fuel mixture in the engine. This process can be done with a simple spark plug tester, and the absence of spark points to potential issues within the ignition system. This article will outline the steps involved in testing for spark, along with identifying common reasons for a lack of spark.
Understanding the Ignition System
Before we dive into testing for spark, let’s take a moment to understand the basic workings of a lawnmower’s ignition system. The ignition system’s primary function is to create the spark that ignites the fuel-air mixture within the engine’s combustion chamber. Here’s a breakdown of the key components:
1. Ignition Coil:
The ignition coil is responsible for generating the high-voltage spark required to ignite the fuel. It works by converting low-voltage electricity from the battery into a high-voltage current.
2. Spark Plug:
The spark plug is the final component in the ignition circuit. It receives the high-voltage spark from the ignition coil and delivers it to the combustion chamber, where it ignites the fuel-air mixture.
3. Ignition Switch:
The ignition switch acts as the on/off switch for the ignition system. When you turn the key to the “start” position, it closes the circuit, allowing electricity to flow through the system.
4. Magneto (for some lawnmowers):
Some lawnmowers, particularly older models, use a magneto instead of an ignition coil. A magneto is a self-contained device that generates electricity through the rotation of the engine.
Checking for Spark: A Step-by-Step Guide
Now that you have a basic understanding of the ignition system, let’s move on to the process of checking for spark. Here’s a detailed guide:
1. Gather Your Tools
Before you begin, make sure you have the following:
- Spark plug tester: This inexpensive tool consists of a wire with a clip on one end and a spark gap on the other.
- Socket wrench: This wrench is used to loosen and tighten the spark plug. Make sure the wrench size matches your spark plug.
- Safety glasses: Always wear safety glasses to protect your eyes from potential sparks.
- Gloves: It’s a good idea to wear gloves to protect your hands from any hot or sharp parts of the engine.
2. Disconnect the Spark Plug Wire
Locate the spark plug wire, which is a thick cable connected to the spark plug. Carefully pull the wire straight off the spark plug, ensuring that you are holding the wire and not the spark plug itself.
Important Note: It’s essential to disconnect the spark plug wire to prevent any accidental ignition when you’re working with the spark plug.
3. Connect the Spark Plug Tester
Connect the spark plug tester’s clip to the spark plug wire. The other end of the tester should have a metal point that you will hold in close proximity to the engine’s metal part.
4. Test for Spark
With the spark plug wire disconnected and the spark plug tester connected, have someone crank the engine while you hold the metal point of the tester near the engine block. Observe the spark gap on the tester. If you see a bright blue spark jumping across the gap, it indicates that your ignition system is working correctly.
5. Repeat the Process
Repeat the test for spark with the spark plug still removed from the engine. This helps ensure that the spark is actually coming from the ignition system and not just a stray current from the spark plug wire itself.
What to Do If You Don’t See Spark
If you don’t see a spark, you need to troubleshoot the ignition system to identify the problem. Here are some of the common reasons for a lack of spark:
1. Faulty Spark Plug:
The spark plug can become fouled with carbon deposits, wear out, or even become damaged. Inspect the spark plug for any signs of damage, corrosion, or carbon buildup. If necessary, replace it with a new spark plug.
2. Broken Spark Plug Wire:
The spark plug wire can become damaged or frayed over time, causing a break in the electrical circuit. Check the wire for any signs of damage, and if necessary, replace it.
3. Bad Ignition Coil:
The ignition coil can fail, preventing the generation of a high-voltage spark. If you suspect a faulty coil, you’ll need to replace it.
4. Defective Ignition Switch:
The ignition switch may not be making proper contact, causing a break in the electrical circuit. Inspect the switch for any signs of damage or corrosion, and if necessary, replace it.
5. Faulty Magneto (for some lawnmowers):
If your lawnmower has a magneto, it could be faulty, preventing the generation of electricity. This typically requires replacing the magneto.
Troubleshooting Tips
While testing for spark can give you a good indication of the problem, it’s not always the end of the story. Consider these additional tips:
- Check the battery: Make sure the battery has enough charge to power the ignition system. A weak battery can cause a lack of spark.
- Check the fuel system: Ensure the fuel line is clear and the fuel tank is full. A fuel problem can prevent the engine from starting, which may lead to a false reading on the spark tester.
- Clean the spark plug: Even if you see a weak spark, cleaning the spark plug can sometimes improve its performance.
- Inspect the engine: Look for any loose wires or connections, as these can also cause ignition problems.
- Seek professional help: If you’re unable to identify the problem after troubleshooting, it’s always best to consult a qualified mechanic for assistance.
Conclusion
Checking for spark is an essential step in troubleshooting a non-starting lawnmower. By understanding the basic workings of the ignition system and following the steps outlined in this guide, you can quickly determine if the lack of spark is the culprit. Don’t let a faulty ignition system keep you from enjoying your lawn. Equip yourself with the knowledge to identify and fix the problem, and get back to the satisfying hum of a running mower in no time!
FAQs
Q1: What is spark, and why is it important for my lawn mower?
A: Spark refers to the electrical discharge that ignites the fuel-air mixture in the combustion chamber of your lawn mower’s engine. This spark is generated by the spark plug, which is a crucial component in the ignition system. Without a strong and consistent spark, your lawn mower’s engine cannot ignite the fuel, and therefore, cannot start.
Q2: How do I check for spark on my lawn mower?
A: To check for spark, you’ll need a spark plug tester. First, disconnect the spark plug wire from the spark plug and ground the wire to a metal part of the engine. Then, crank the engine while observing the spark plug tester. If you see a strong blue spark, it indicates that your ignition system is working correctly. However, if the spark is weak, intermittent, or absent, there might be a problem with the spark plug, ignition coil, or other components of the ignition system.
Q3: What if I see a weak or intermittent spark?
A: If you observe a weak or intermittent spark, it could be a sign of a worn-out spark plug, a faulty ignition coil, or a problem with the ignition system’s wiring. It’s recommended to replace the spark plug first, as it’s the most common culprit. If the issue persists, you may need to investigate the ignition coil or wiring for any damage or loose connections.
Q4: What if there is no spark at all?
A: If there’s no spark at all, it could be an issue with the spark plug, ignition coil, ignition module, or even a broken wire in the ignition system. You should start by checking the spark plug and ignition coil for any damage or corrosion. If everything seems fine, then you might need to diagnose the ignition module or the wiring.
Q5: How do I replace the spark plug?
A: To replace the spark plug, first, disconnect the spark plug wire. Then, use a spark plug wrench to loosen and remove the old spark plug. Be sure to discard the old spark plug properly. Now, screw the new spark plug into the cylinder head, hand-tighten it, and then use the wrench to tighten it to the recommended torque specification. Finally, reconnect the spark plug wire.
Q6: Should I use a specific type of spark plug?
A: Yes, it’s crucial to use the right type of spark plug for your lawn mower engine. The manufacturer’s manual will specify the correct spark plug type, including the heat range and thread size. Using the wrong spark plug can lead to poor performance, engine damage, or even safety issues.
Q7: What are some other reasons my lawn mower might not be starting?
A: Besides a lack of spark, other factors can prevent your lawn mower from starting, including a clogged air filter, a bad fuel supply, a dead battery, or a flooded engine. If you’ve ruled out spark issues, consider inspecting these areas to diagnose the problem.