How To Check If Lawn Mower Spark Plug Is Firing [3 Easy Methods]

How To Check If Lawn Mower Spark Plug Is Firing

Have you been having issues with your lawnmower lately? If so, there’s a good chance that bad spark plugs are to blame. But, how to check if the lawn mower spark plug is firing or not? if you don’t know how to check them, worry not! We’re going to give you an ultimate guide on how you can do it, so stick around!

The spark plug is a vital component of the engine that provides ignition to the combustion chamber of the engine by mixing an accurate ratio of fuel and air through an electric spark.

By the end of this guide, you should have no problems diagnosing and fixing the issue with the lawnmower spark plug. So, without further ado, let’s get started!

How To Check If Lawn Mower Spark Plug Is Firing

In this guide, we’ll be teaching you 3 different techniques to check if your lawn mower’s spark plugs are firing. We’ll also give you a few tips on what to do if they’re not firing properly.

  • With a spark plug tester
  • With a screwdriver
  • Without any tool
Lawn mower spark plug
Original Equipment Manufacturer (OEM) part
Compatible Brands: Craftsman, Tecumseh, Mtd, Sears, Troybilt
Spark Plug Tester
Gives a Visual Check of the Ignition System
Quickly diagnose problems in the entire ignition system
Double-ended tool to offer a straight boot and a 90boot
Flashes a mirror image of the ignition spark
Neon Tube Light Display
Display light when detecting electricity
• Measures circuit electrical pen
Act as a screwdriver as well
Nylon Bristel Brush Set
Made of brass, stainless steel, and nylon
Strong and Durable
Rust Resistant
Suitable for cleaning and removing Dust, Rust, and loose paint

Step1: Check if Spark Plug is Firing With A Spark Plug Tester

The spark plug tester is a key tool to diagnose whether your vehicle’s plugs are healthy and ready for action. This device can be used with either inductive or Dielectric tests, depending on how much time you have available!

With a spark plug tester

To start your lawnmower, both the plug tester and the ignition coil needs to be connected. The first turn on the plug tester powers up this battery while also connecting it with whatever ignition coil is present in order for you to unlock ALL power from within!

  1. Turn the engine off and make sure to disengage all the electric supplies.
  2. Remove the engine cover by lifting it.
  3. Locate the exact location of the spark plug in the engine to disconnect it.
  4. Pull the ignition coil to remove it from the spark plug and ground the plug by attaching it to the metal surface of the engine.
  5. Replace the spark plug with the ignition tester and make sure to ground the tester by connecting it with the metal covering.
  6. Connect the tester in between the spark plug and the ignition coil by connecting one end with the ignition coil and the other one with the spark plug.
  7. Turn on the ignition by starting the engine.
  8. If you can see the fire or a spark in the tester while starting the engine, then you have no issues with the spark plug, and you are getting a spark.
  9. If the tester is out of fire or spark, then you need a spark plug replacement.
using spark plug tester

Step2: Check If Lawn Mower Spark Plug Is Firing With A Screwdriver

Using a screwdriver is another significant technique to check if your spark plugs are working properly.

This is a tool that has two ends. One end is for screws and the other end is for light. When you use it on things like terminals or wires, you need to twist and turn it in a precise way. This is so you can see if they are in the right place before continuing. If you don’t do this, the engine block might leak oil.

  1. Remove the engine lid and locate the spark plug.
  2. Check for the ignition coil and pop it off from the spark plug.
  3. Stick a screwdriver inside the ignition coil.
  4. Then bring this coil and screwdriver close to the engine while keeping your engine ground.
  5. Get close to about half of a quarter inch and crank the engine.
  6. If your ignition system is working well, then you should feel a zapping over the screwdriver.
  7. If you are not feeling anything, then you need to replace the spark plug.
with a screwdriver

Step 3: Check If Lawn Mower Spark Plug Is Firing Without Any Tool

Sometimes, you might find yourself in a situation where there are no tools available.

However, if your spark plugs have been burning for some time and show no signs of stopping soon then this is an option that can be used to test them before replacing the whole engine!

This is how it works;

  1. You need to remove the spark plug from the engine.
  2. Reconnect it with the ignition coil or the spark plug coil.
  3. Ground the spark plug by attaching the threaded part of the plug to the metal surface of the engine.
  4. Make sure to unplug the fuel pump connection and supply from the engine.
  5. Start the engine to check the spark plug is firing.
  6. If the plug is functioning correctly, then you will be able to see a spark at the tip of the plug. Otherwise, you have a damaged or failed spark plug.
Without any tool

Important Instructions – How To Check If Lawn Mower Spark Plug Is Firing

  • Keep your hands off of the coil and the tester while checking for the spark.
  • Spark plug fire testing with a screwdriver is not secure and safe.
  • A screwdriver is a dirty and highly not recommended method of spark testing.
  • Keep your hands off the engine and machine while starting the engine to prevent any injury because of high voltage.
  • Make sure to have a backup battery source while checking for the firing spark plug.
  • You can use a soft wire brush to clean the spark plug.
  • Avoid using blaster for spark plug cleaning purposes.
  • Make sure to check and replace the spark plug as needed after some duration to keep the lawnmower efficient.

As a homeowner, you should be aware of the importance of spark plug cleaning and maintenance. It’s essential to keep your lawnmower running efficiently so that it will not only last longer but also provide more power for cutting grass in perfect shapes!

By following this guide, you will be able to check and maintain your lawn mower’s spark plug without any issues. And now that we’ve shown how easy it is at home with a little know-how!

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