How to Check a Coil on a Lawn Mower [Testing Guide]
If you’re a homeowner or avid gardener, chances are you’ve had to deal with a balky lawn mower at some point. One of the most common culprits behind a mower that won’t start or run properly is a faulty ignition coil. But don’t worry, diagnosing and replacing a bad coil is a pretty straightforward process that even DIY enthusiasts can tackle.
In this comprehensive guide, we’ll walk you through the steps to check a coil on your lawn mower, so you can get your trusty machine back up and running in no time. Whether you’re dealing with a riding mower, push mower, or even a zero-turn model, the principles are largely the same. So, let’s dive in and learn how to troubleshoot that stubborn coil!
What is a Lawn Mower Ignition Coil?
The ignition coil on a lawn mower is a vital component of the engine’s ignition system. Its primary function is to convert the low-voltage current from the battery or magneto into the high-voltage spark needed to ignite the fuel-air mixture in the engine’s cylinders. Without a properly functioning coil, your mower simply won’t start or run reliably.
Signs of a Bad Lawn Mower Coil
Before we get into the nitty-gritty of testing the coil, let’s first look at some common symptoms that might indicate a problem:
- The engine won’t start or is difficult to start
- The engine starts but then stalls out
- The engine runs rough or misfires
- The engine loses power or doesn’t reach full RPMs
These are all potential signs that the ignition coil on your lawn mower is failing and needs to be checked or replaced. Of course, there could be other underlying issues, so it’s important to do a thorough diagnosis before jumping to conclusions.
How to Check a Coil on a Lawn Mower
Now, let’s get into the step-by-step process for testing the ignition coil on your lawn mower. This guide will work for both ride-on and push mowers, as the basic principles are the same.
Gather the Necessary Tools
Before you get started, make sure you have the following tools on hand:
- Multimeter or ohmmeter
- Spark tester or spark plug wire
- Socket set or wrench
- Work gloves (optional)
Having the right tools will make the testing process much easier and more accurate.
Locate the Ignition Coil
The first step is to locate the ignition coil on your lawn mower. This is typically mounted near the engine, often near the spark plug wires. Consult your mower’s owner’s manual if you’re unsure of the exact location.
Visually Inspect the Coil
Once you’ve found the coil, do a quick visual inspection. Look for any signs of damage, such as cracks, burns, or loose connections. If the coil looks visibly damaged, it’s likely time for a replacement.
Test the Coil with a Multimeter
If the coil looks okay on the outside, it’s time to check the internal resistance using a multimeter or ohmmeter. Here’s how:
- Disconnect the spark plug wire from the coil.
- Set your multimeter to the ohms (Ω) setting.
- Touch the multimeter probes to the two terminals on the coil. The resistance should be within the range specified by the manufacturer, typically between 0.5 and 5 ohms.
- If the resistance is outside of this range, the coil is likely faulty and needs to be replaced.
Perform a Spark Test
If the coil passes the resistance test, the next step is to check for a spark. Here’s how:
- Reconnect the spark plug wire to the coil.
- Remove the spark plug from the engine.
- Connect a spark tester or hold the spark plug wire about 1/4 inch from a metal surface on the engine.
- Turn the engine over and look for a strong, consistent spark. If there’s no spark or a weak one, the coil is likely faulty.
Replacing a Lawn Mower Ignition Coil
If your testing has confirmed that the ignition coil is indeed the culprit, it’s time to replace it. This is a relatively straightforward process, but be sure to follow the manufacturer’s instructions carefully.
Order the Correct Replacement Coil
Before you can replace the coil, you’ll need to make sure you have the right part. Check your owner’s manual or the manufacturer’s website to find the specific model number for your lawn mower, and order the correct replacement coil.
Remove the Old Coil
Once you have the new coil, unplug the spark plug wire and remove any mounting hardware or screws holding the old coil in place. Be gentle to avoid any damage to the surrounding components.
Install the New Coil
Carefully install the new coil, making sure all connections are secure. Reconnect the spark plug wire and any other wiring. Double-check that everything is properly aligned and tightened down.
Test the New Coil
Finally, perform another spark test to ensure the new coil is working correctly. If all looks good, you can reassemble your lawn mower and give it a test run.
Conclusion
Diagnosing and replacing a faulty ignition coil on a lawn mower may seem daunting, but it’s actually a relatively straightforward process that even novice DIYers can handle. By following the steps outlined in this guide, you’ll be able to quickly identify the issue and get your mower back in top shape.
Remember, regular maintenance and troubleshooting can go a long way in keeping your lawn mower running smoothly for years to come. So, don’t be afraid to roll up your sleeves and tackle that stubborn coil – it’s a skill that will serve you well as a homeowner or gardener.
FAQ
How do I know if my lawn mower’s ignition coil is bad?
Some common signs of a bad lawn mower ignition coil include the engine not starting, stalling, running rough, or losing power. You can also test the coil with a multimeter or perform a spark test to diagnose the issue.
Can I replace a lawn mower ignition coil myself?
Yes, replacing a lawn mower ignition coil is generally a DIY-friendly task. Just make sure to have the right tools, follow the manufacturer’s instructions, and test the new coil to ensure it’s working properly.
How much does it cost to replace a lawn mower ignition coil?
The cost to replace a lawn mower ignition coil can vary depending on the make and model, but it’s typically a relatively inexpensive repair. Expect to pay anywhere from $20 to $100 for the replacement part, plus any labor costs if you have a professional do the work.
How often should I replace the ignition coil on my lawn mower?
There’s no set schedule for replacing a lawn mower ignition coil, as it depends on the specific use and wear and tear. However, it’s a good idea to inspect the coil annually and replace it if it’s showing signs of wear or damage.
Can a faulty ignition coil cause a lawn mower to backfire?
Yes, a faulty or failing ignition coil can absolutely cause a lawn mower to backfire. This is because the inconsistent or insufficient spark from a bad coil can lead to unburnt fuel being ignited in the exhaust system, resulting in that distinctive backfiring sound.
