Lawn mower coil gap. Honda Lawn Parts Blog

Why Is My Lawn Mower Not Firing? (How To Troubleshoot)

Have you ever undergone a situation where your lawn mower won’t fire up? If yes, you must have wondered what might have gone wrong and whether it is possible to troubleshoot this issue. You must have also wondered how to troubleshoot such a problem.

Firstly, test whether there’s any Spark or not. Next, remove all cover parts to access the Ignition coil. Then, remove the older one and install the new Ignition coil accordingly. Adjust the Gap between the Flywheel Ignition coil. Lastly, reinstall all the parts recheck the Spark.

Thus, continue reading the following article and learn how to troubleshootwhy is my lawn mower not firing.

What Causes the Problem?

A lawn mower might experience no firing or no spark issue due to defective internal elements of the ignition system. Such as faulty Armature or ignition coil, broken or damaged spark plug, or loose or disconnected internal wiring connections.

Not firing trouble can also arise on a lawn mower due to a bad plug gap, a wrong gap between the flywheel and the ignition coil, loose or disconnected coil control wiring, faulty grounds or shorts, and a defective stop/start switch.

However, all of those are just assumptions based on most users’ and experts’ experiences. You can only confirm the actual culprit of such commotion after you have thoroughly investigated all the possible faulty areas.

Steps to troubleshoot why is my lawn mower not firing:

Lawn mower users often complain about why is my lawn mower not firing.

It can arise due to various reasons such as dirty or worn-out spark plugs, bad ignition coil, kill switch malfunctioning, defective stop switch, broken wires, shorts, or ground issues.

But you cannot verify until you have investigated all the possible foul areas to confirm the main defective part.

Adjusting Ignition Coil Air Gap Honda GX390

Inspecting each and every possible internal area is a great way, but it can be time-consuming and expensive too.

In that case, most people prefer a short and simple way to fix the problem.

That’s why I have enlisted a quick, simple, and cost-effective DIY method to troubleshoot such issues.

Things needed to troubleshoot why is my lawn mower not firing:

Have a proper glance at the checklist of the required tools and materials:

Tools Materials
Standard Mechanical tool box New ignition coil
Safety Gloves Goggles

Step 1- Test whether there’s any Spark or not:

First, start the process by removing this spark plug.

Next, put the plug back in here, and reconnect it.

Then, lean it here against the engine block and try to start your lawn mower engine to check if there’s any spark.

You can see in the below image there’s no spark, right?

Therefore, you need to check on the ignition coil next.

Step 2- Remove cover parts access the Ignition coil:

First, remove all the cover parts that shield the ignition coil here.

Keep removing all the parts until you reach the flywheel and ignition coil.

Now access to the ignition coil here.

This little black wire, that’s your kill switch wire.

In case, it is loose and leaning against something else, then that’s already a problem. So, make sure that the wire is correctly assembled. Otherwise, there will be no spark or no firing.

Then, you have this gap between the flywheel and the ignition coil. Thus, make sure that gap is correct.

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Then, carefully remove the ignition coil by disconnecting the wire as shown in the picture.

Step 3- Install new Ignition coil:

If the ignition coil looks bad in shape or condition, replace it with a new one.

Now connect that wire to the new ignition coil and reassemble the ignition coil in the same way as you removed the older one.

Step 4- Adjust the Gap between the Flywheel Ignition coil:

Next, you need to adjust the gap between the flywheel and ignition coil.

Take a simple piece of paper and fold this in half.

Now see these magnets here, and those magnets should be right in front of the ignition coil.

So, loosen the brake to move the magnets in front of the ignition coil.

Since it’s magnets the ignition coil is going to draw.

So, pull the ignition coil away a little bit and take that paper to put in between.

Now, it’s easier to tighten the screws securely. When you have successfully secured the screws, remove the paper.

Tips: Remember gap distance between the flywheel and the ignition coil should be point 1 and point 3 millimeters.

Again, loosen the brake and rotate the flywheel to ensure there are plenty of gaps and no contact between them.

Step 5- Reinstall all the parts recheck the Spark:

Now, put back all the upper parts that you previously removed to access the ignition coil.

You can even take pictures of every step; in case you mess up later on.

Then, connect the spark plug against the engine block and pull the bolstering. If you can see the spark, it means your problem is solved.

Next, put everything back together and fire it up to see what happens. If it is working, you are good to go now.

If you still see that your mower not firing up, contact the nearest dealership for professional assistance.

Performing such troubleshooting tasks can be hazardous. Thus, make sure you have enough knowledge and expertise to perform them. Always read your mower’s instructions manual first before operating, servicing, or troubleshooting it.

Frequently Asked Questions

What causes a lawn mower to not get spark?

It can occur due to defective wires, faulty spark plug lead, shorts, grounds, damaged ignition coil, or a damaged stop switch.

Why does my lawn mower cylinder not fire up?

When you notice that your lawn mower engine has started to misfire, it’s obvious that one or more cylinders are not producing enough power. Such failure can arise due to a fouled spark plug, faulty oxygen sensor, or clogged fuel injector.

How to determine when your lawn mower ignition switch is bad?

Common symptoms such as a stuck ignition key, the engine doesn’t turn on, unable to move the ignition key back and forth or engine cranks then die will alarm you about a bad ignition switch.

Can a bad ignition coil on a lawn mower cause engine to fail to start?

Yes, it can. When the ignition coil turns bad, it fails to transfer the required voltage, and the engine will fail to fire up. This will eventually lead to a no-start situation.

Final Verdict

Initially, the whole procedure might seem a bit complicated to perform, but with minimum mechanical expertise, you can easily fix the issue by thoroughly following the steps explained above. Thus, if you encounter similar issues with your lawn mower in the future, do not wonder why is my lawn mower not firing. Instead, try today’s DIY technique to fix it.


Troubleshooting Your Honda’s Ignition System

Is your Honda engine not wanting to start? Is it running rough, despite everything being fine with the fuel system and air filter? It may be having an issue with the ignition system. Here’s what you need to know to troubleshoot common electrical problems on these motors.

Before You Begin

If the engine has been running, it needs to be left to cool for at least a half hour before working on it to prevent burns.

To access the flywheel on some models, the engine shroud/starter cover needs to be removed. On GCV models, this shroud is connected to the fuel tank. If the engine has a fuel valve, turn it off before unbolting the tank, and make sure the tank is tilted over a container to catch any fuel that leaks out.

Honda Oil Alert and Kill Switches

Most recent engines come equipped with Honda’s Oil Alert system, which shuts down the engine if the oil in the crankcase is too low, preventing internal damage. This system works by wiring a float into the ignition system: if the float is too low, the ignition circuit is cut, which prevents the spark plug from firing. Generators and engines with a built-in console will have a light that indicates whether or not the system has been activated. For other engines, the only way to see if the system may have tripped is to check the oil level.

Most engines also come equipped with kill switches that will cut power to the ignition system. This switch will be located on the engine, but it may be operated from a remote location, such as a bail on a lawn mower handle. Both the kill switch and the Oil Alert float connect to a single wire on the side of the coil. If this wire is damaged or becomes disconnected, the spark plug won’t fire. If the kill switch is damaged, it will need to be replaced. There should be two wires next to the switch that can be disconnected by pulling them apart, as well as a grounding tab located on the back of the switch that should be bent back. On most models, the starter cover will need to be removed to access the tab.

Power Generation and Ignition

In a car, the power generation system is contained in the alternator, but in a small engine, the generator components are separated and mounted on and around the flywheel. When the engine is running, magnets on the flywheel pass by a coil, creating electricity. This electricity is stored in the coil until it is needed.

Modern Honda engines use a solid state ignition system that uses a transistor to control when the electricity is sent through the spark plug wire. The coil, transistor, rectifier and spark plug wire are built as one unit. Once the piston is in the right position, the electricity in the coil is released, creating an arc of electricity across the electrodes of the spark plug, igniting the fuel.

If the flywheel is damaged or the key that keeps the flywheel in position on the crankshaft has fallen out or sheered off, the timing will be off. If the insulator inside the coil has worn out or the insulator over the spark plug wire is damaged, there won’t be enough electricity making it to the plug to ignite the fuel.

When replacing the coil, there needs to be a small gap between it and the flywheel. The easiest way to set this gap is to place a business card between the flywheel and the coil, then tighten down the bolts enough to keep the coil in position. A feeler gauge can be used to set the correct gap, specified in the repair manual, before fully tightening the bolts.

Spark Plug

For most engines, Honda recommends replacing the spark plug at least yearly, while each model has recommendations based on operating hours. A worn electrode will have too wide of a gap to get a good arc, while a damaged insulator could be shorting out the spark plug, transferring power to the engine instead of out through the electrodes.

Husqvarna Coil Problems

Husqvarna is a trusted name in the lawn care industry. But like any other brand, they’re not immune to coil problems. The most common issue with Husqvarna coils is that they fail to produce a spark.

This can be caused by several things, including a dirty spark plug or bad ignition module. Sometimes, simply replacing the coil will fix the problem. Other times, you may need to replace the entire ignition system.

If you’re a Husqvarna owner, you may have experienced coil problems. The good news is that there are ways to fix this issue. In this blog post, we’ll discuss the most common coil problems and how to solve them.

The first problem is that the coil can become damaged. This can happen if the engine backfires or if the ignition system fails. If your coil is damaged, it will need to be replaced.

Another common problem is that the wires can become loose. This can cause the spark plugs to misfire. To fix this, simply check the wire connections and make sure they’re tight.

Another issue that can occur is that dirt and debris can build up on the coils. This can cause them to overheat and fail. To clean your coils, simply remove them from the engine and use a soft brush to remove any dirt or debris.

If you’re having trouble with your Husqvarna’s coils, don’t despair! There are ways to fix these issues so you can get back to enjoying your lawn mower again in no time!

Husqvarna Ignition Coil Gap

If you have a Husqvarna chain saw, you know that it’s a reliable and powerful tool. But like any machine, it needs regular maintenance to keep it running smoothly. One important part of maintaining your Husqvarna is adjusting the ignition coil gap.

The ignition coil on a Husqvarna chain saw produces the spark that ignites the fuel mixture in the engine cylinder. Over time, the coils can become worn or damaged, which can cause them to lose their ability to create a strong spark. When this happens, it’s necessary to adjust the gap between the coils.

Adjusting the ignition coil gap is a relatively simple process. First, remove the spark plug from the engine so you can access the coils. Then use a feeler gauge to measure the gap between the coils.

If necessary, use a small file or piece of sandpaper to widen or narrow the gap until it’s within specification. Once you’ve adjusted the ignition coil gap, re-install the spark plug and start up your Husqvarna chain saw to make sure everything is working properly. With just a little bit of preventive maintenance, you can keep your chain saw running like new for years to come!

Husqvarna Ignition Coil

If your Husqvarna lawn mower won’t start, one possible reason is a faulty ignition coil. The ignition coil on a Husqvarna lawn mower is responsible for generating the spark that starts the engine. If the coil is defective, it may be producing a weak spark or no spark at all.

In either case, the result is an engine that won’t start. There are a few signs that may indicate your Husqvarna’s ignition coil needs to be replaced. If you notice any of these symptoms, it’s time to check the coil:

-The engine cranks but won’t start.The engine starts but runs poorly or stalls soon after starting.There is visible damage to the coil

If you suspect your Husqvarna’s ignition coil is faulty, you’ll need to replace it with a new one. You can purchase a replacement coil from your local Husqvarna dealer or online retailer. Be sure to get the correct model number for your lawn mower so you get the right part.

Installing the new ignition coil is relatively easy and can be done in just a few minutes with basic hand tools. Simply remove the old coil and install the new one in its place. Once installed, test out your lawn mower to make sure it starts properly.

Husqvarna Ignition Coil Specs

Husqvarna ignition coils are designed to give your engine a spark that is hot enough to ignite the fuel mixture in the cylinders. The Husqvarna company produces a variety of outdoor power equipment, including lawn mowers and chainsaws. The company’s website has detailed specifications for all of its products, including ignition coils.

The specifications for Husqvarna ignition coils vary depending on the model of coil. For example, the specs for the Husqvarna 51 Ignition Coil include an output voltage of 12,000 volts and a primary resistance of 0.6 ohms. The specs for the Husqvarna 61 Ignition Coil include an output voltage of 11,000 volts and a primary resistance of 0.7 ohms.

When choosing an ignition coil for your Husqvarna product, it is important to select one that is compatible with the model number of your machine.


If you’re a Husqvarna owner, you may have experienced coil problems. The coils can go bad for a number of reasons, including exposure to moisture, age, or simply wear and tear. If your coils are bad, it’s important to replace them as soon as possible.

Here’s a quick guide on how to do just that.

Lawn Mower Coil Good But No Spark: A Complete Guide

You are ready to mow your beautiful lawn. Unfortunately, your lawn mower doesn’t spark up. So what causes the lawn mower coil good but no spark ?

There are multiple causes for this issue. We will discuss them one by one and recommend the best solution for each case. Let’s get started!

Causes Of Lawn Mower Coil Good But No Spark

While your lawn mower coil is still good, it can’t spark because of the improper coil air gap, loose magnets, rusty flywheel, or faulty ground wire.

Coil Air Gap

The flywheel’s magnet passes by the coil, generating an electric charge that goes to the spark plug. For this process to work efficiently, the gap between the coil and magnet should be at the recommended distance.

Lawn mower Ignition Coil Why/How can FAIL! Know this Lawnmower during Coil Test!

You should adjust the gaps on both sides of the coil yoke to the suggested distance. The coil won’t create the needed electric charge if the yoke distance or the overall gap is wrong. Sometimes, it makes the spark plug keep fouling.

In simpler terms, if the settings are wrong, the coil can’t work. To check the gap, you can use a feeler gauge after checking the manual for the recommended coil air gap distance.

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You can also measure the gap by sliding the feeler gauge between the flywheel magnet and the coil on your lawn mower. If it’s not correct, then adjust it.

Flywheel Magnets

As the flywheel spins, the magnet inside will pass by the coil. Over time, magnets may weaken, but it is not a significant concern for lawn mowers.

However, the magnets can become misplaced or loose, affecting the machine’s performance. So, it’s essential to check if they are in the correct position inside the flywheel.

You need to look at the flywheel to locate the magnets. The manufacturer should mark or polish them. Then, to test them, hold a metal object close to the flywheel. If you don’t see any attraction, you will need to solve this problem.

Corrosion of the Flywheel

Flywheels made of cast iron rust over time and will weaken the magnetism movement to the coil. This issue causes the coil to become non-functional.

To check for any corrosion, you can remove the cover of the lawn mower and inspect the flywheel.

Please note that this problem is not common in new lawn mower models. The alloy flywheels of such machines are rust-resistant.

Flywheel Ground/ Coil Ground

When you release the bail lever on the handlebar of your lawn mower, there will be a direct ground connection between the engine and the coil. The spark created by that interaction will stop the engine.

In this case, the bail lever is the switch to charge the engine or the spark plug. So if there’s a problem with the bail lever ground, the coil might remain constantly grounded.

To test the ground wire of the coil, please follow these steps:

  • Detach the ground wire.
  • Disconnect and remove the spark plug from the lawn mower.
  • Attach the spark plug tester to the spark plug cable and the engine.
  • Turn the engine over and check the light of the tester. If you see the light, the coil ground must be faulty. And if the tester doesn’t light, the coil can be the cause of the problem.

Solutions Of Lawn Mower Coil Good But No Spark

Your lawn mower coil may be good but doesn’t spark for four reasons. Here is how you deal with each case:

Gap the Coil

To adjust the gap of your coil, you’ll need a feeler gauge and a specific gap distance for the lawn mower. Then, follow these steps to fix it:

  • Align the flywheel magnets with the coil, then insert the feeler gauge.
  • Use a socket wrench to loosen the two bolts holding the coil to your engine. While performing this step, the magnet’s force will pull the coil towards the flywheel.
  • Next, tighten the two bolts using the socket wrench.
  • Remove your feeler gauge and spin the flywheel. Ensure the flywheel does not touch the coil.

Repair the Magnets

To fix loose magnets, you’ll have to remove the flywheel. The instructions are as follows:

  • Use a socket wrench to unscrew the center nut at the top of the wheel.
  • Remove the flywheel from the engine. Once you flip it, you will notice that the magnets have come loose.
  • Apply a solid two-part glue to the contact side of the loose magnet and put it back on the flywheel.
  • Let the glue set overnight to ensure it fully dries.
  • When the glue has cured, put the flywheel back in place and tighten the center nut.
  • Examine the coil gap and reassemble the rest of the mower.

Remove the Corrosion

If your flywheel is rusty, use sandpaper to rub the affected part. You don’t need to make it shine; just remove as much rust as you can.

Besides, remember to clean the components of your lawn mower regularly. Otherwise, they lead to several issues, such as the spark plug turning black or faulty blades.

Repair the Coil Ground

The coil ground wire is a short wire with connectors at both ends. One end links to the coil, while the other is on the bail lever.

To fix the ground wire, find the connector on the coil and disconnect it. Then, trace the wire back to locate the other end connected to the bail mechanism.

You may notice that the other end of the wire has a ring connector or just a connector. If it’s the ring one, remove the screw using a screwdriver.

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After that, connect the new wire to the bail mechanism and the coil. It’s a quick fix, but a faulty wire can still cause a good coil to have no spark.


With the know-how to troubleshoot a lawn mower coil that’s good but lacks a spark, you can now confidently tackle this issue.

Now, grab your tools and follow our tips. You can enjoy the satisfaction of a perfectly mowed lawn.