Why Is My Lawn Mower Spark Plug Wet? (3 Possible Problems+Fix)

Is the spark plug or ignition cable of your mower wet sometimes? If yes, this problem usually occurs when your lawnmower assimilates with liquid or gas.

A spark plug is wet when there is oil leakage in the combustor or if the engine gets in contact with fuel or water. Sometimes you might also find a wet spark plug in older lawnmowers because the compression rings have worn out, which has flooded the engine with excessive oil or gasoline.

This article will explain the reasons behind a soaked spark plug in a lawn mower and how we can fix it. So, let’s get started. 

Lawn mower spark plug removal

Signs of a wet spark plug (Ignition cable)

A spark plug is one of the most important components in a lawn mower that helps the engine to generate power by providing it with a spark.

Hence, any disruption in the spark plug can lead to the malfunctioning of your mower.

When the lawnmower’s ignition cable is wet, it will show you the following signs:

1. Your mower will be hard to commence

If the ignition cable becomes wet, it will fail to generate the spark required to burn the fuel and turn on the engine. 

2. Your mower will not work properly

The lawn mower will fail to perform optimally.

It will dry out, produce choking noises, and will move unsteadily. 

This problem can happen due to a damaged spark plug that can cause a blunder in the engine.

3. Your mower will use an excessive amount of fuel

If there is a default in a spark plug, the mower efficiency will get reduced, and the fuel consumption will be high.

Also, you may get a bad odor from the engine. 

Why is the spark plug getting wet?

Lawn mower spark plug

Below are some reasons for it to get wet:

To fix the spark plug, you will need to clean or change it to make it work.

But before making any move to clean or change the spark plug, you will need to find out why it was wet. 

A few reasons that can cause it to be wet in a lawn mower are:

1. Leaks in the injector

A spark plug can get wet due to technical issues, also.

Leakages in a cold start injector are a common problem that the lawn mower engine might encounter. 

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2. A flooded engine

When we try to start the lawn mower machine, it sometimes fails.

If we try to start the lawn mower multiple times, the engine may get flooded, making its spark plug wet.

The engine will face flooding issues in freezing weather.

The lawn mower’s engine will require high voltage to get started if it becomes old and greasy. 

You will need to clean the spark plug in this situation.

3. Compression rings started to worn out

The spark plug might start fouling if the compression rings have worn out due to the older engines of the lawn mower.

This situation causes the lawnmower engine to flood with excessive oil or gasoline.  

As a result, you won’t be able to start the lawn mower if the ignition doesn’t form. 

However, you can fix the problem with your mower’s spark plug if you take it out and cleanse it.

Once cleaned, reinstall the spark plug and check whether the lawn mower is working.

How can gas wet the spark plug?

Lawn mower spark plug fix

The spark plug’s main function is to kindle the air or fuel mixture when you start the lawn mower.

Since a spark plug is an electrical device, keeping it in good condition and away from wetness is always better.

However, if it is soaked with oil or gasoline, it will cause engine flooding. 

There can be numerous reasons that can cause the ignition cable to get wet due to gas.

A flooded engine, damaged ignition cable, ceramic insulator, internal cracks or dirt, and moisture can cause it to be wet.

If gas is the cause behind a wet spark plug, the electrodes still need to be ignited. 

However, if the ignition cables turn bad, the components will fail to carry the required conduction under a massive load.  

All these reasons cause the spark plug of lawnmowers to get wet due to gas.

How does oil cause the ignition cable to get wet?

You can get an idea of the conditions of the ignition cable of your lawnmower by looking at its tips.

By looking at the texture and the pigmentation of deposits, you can find other problems too.

The lawn mower will stop working if its spark plug has turned extremely warm and there are oil leakages in the chamber. 

It can get oily for various reasons, like using the choke or spark plug excessively. 

Let us discuss these reasons in detail.

1. If a spark plug is used for extended periods

As per experts, you should change your mower’s spark plug every two years.

But if you heavily use the lawn mower, the spark plug might get damaged quickly, and you will require to change it. 

2. If the choke is excessively used

An exceeded choke usage will result in a huge amount of fuel wastage in the engine.

Also, don’t overprime the mower since the primer is for improving combustion.

3. If the float chamber is stuck

A float chamber helps to regulate the supply of liquid in the system automatically in a mower.

Oil can also get the spark plug wet if the float chamber becomes inefficient in taking charge of the quantity of fuel supplied in the system. 

How can fuel wet the spark plug?

Lawn mower engine repair 4

Fuel fouling is when the spark plug gets wet due to fuel.

The spark plug will get wet due to fuel, especially if there is some problem with the carburetor.  

The fuel in the spark plug will prevent the lawn mower from working efficiently in the garden.

This problem can happen if the throttle is fixed too tightly, due to which the spark plug will not get sufficient air. 

This problem will further lead to loss of power, and the engine with stop performing.

Many times, in this situation, the engine can misfire. 

To fix this problem, turn off the fuel tap until a qualified mechanic fixes the carburetor. 

Clean the fuel as soon as possible to prevent it from reaching the engine.  

Turn off the ignition after you have mowed your garden.

Why my spark plug is wet and black at the same time?

A spark plug can be wet and black at the same time due to various reasons.

This problem will happen if you run the lawn mower continuously, which can lead to too much fuel injection into the cylinders. 

It will result in the ignition cable being coated in unburned fuel, making it black and wet.

Another reason for a black spark plug is when the engine becomes hot. 

It causes it to overheat and turn black and wet. 

If you find your mower’s spark plug wet and black, then get it checked by a professional. 

Never ignore such a problem, as this will result in serious engine damage.

What will happen if you use a wet spark plug?

Lawn mower 1

One basic problem with a drenched spark plug is engine flooding.

This issue mainly occurs when you try commencing the lawn mower several times.

As a result, the spark plug will misfire if it is wet for a long time. 

Therefore, the current generated will flow over a non-conductor such as fuel/gas/oil and damage the engine.

If you find out the cause behind your wet spark plug, take immediate preventive measures before your mower stop working permanently.

What happens to the spark plug if water seeps into it?

Different factors can get the spark plug wet with water.

One common reason that causes it to be wet is the engine not getting sufficient air. 

Another reason that causes it to become wet is when it has become dirty due to lack of cleanliness. 

Other reasons, such as rain, wet grass, and environmental moisture, can make the spark plug wet. 

If there is water in the spark plug, the engine will not start. 

You can prevent this problem by cleaning the spark plug.

However, there is no certainty that this problem might not occur again. 

Water can cause the ignition cable to get a blown head henceforward. 

But mostly, water in the spark plug will cause the machine to stop working while mowing.

How to fix a wet spark plug of a lawn mower?

Lawn mower in snow

If you know about repairing machines, then you can fix them yourself.

However, before taking any step, you will need to identify the real issue your mower is facing and take action accordingly. 

You will need to find out the source of a wet ignition cable, whether it is due to fuel, water, oil, or gas. 

If you need more clarification about the actual cause of wetness, you can visit a nearby repair shop and take help from them to fix the machine. 

Visiting a technician is the best solution as they will have the necessary tools and are trained in their work, and will fix your mower quickly. 

If the ignition cable is damaged, they will replace it with a new one.  

Replacement is the best solution if you can’t identify what’s wrong with your mower’s spark plug.

How to remove water from a spark plug at home?

You can easily clean a wet ignition cable home with a wire brush.

After cleaning the spark plug, you must dry it before using it again. 

First, take out the spark plug from the engine.

Then with the help of a brush, clean the debris, oil, water, fuel, or any deposits.

After cleaning it, allow it to dry for some time.

Once the spark plug dries out, reinstall it into the engine and start it again. 

Tips for stopping wet spark plug in lawnmower

Lawn mower bag

Here are some tips that will help you prevent the spark plug from going wet:

  1. Ensure to leave your mower outdoors during the rainy season.
  2. Never over-prime your mower machine. 
  3. Avoid mowing the garden if your lawn grass is drenched.
  4. Check the lawn mower for any fluid build-up.
  5. Replace the fuel/oil following a fixed period. (every 50 hours)

Final words

If your mower’s spark plug gets wet, it indicates that it has come in contact with oil, fuel, or water. The drenching can happen due to a leaky carburetor, broken seals, etc.

If you see that the spark plug remains constantly wet, serious engine damage will occur. However, you can fix the soaked spark plug after cleaning and drying it.

But even after that, if your mower isn’t working, you will need to get it checked by a qualified mechanic. So that the cause of the damage is detected and necessary changes can be made.

Can you reuse a wet spark plug?

Yes, you can reuse a wet spark plug after cleaning it. However, you might not get the same efficiency.

How long does a spark plug take to dry?

A spark plug can take around 1 day to get dry.

Reference: Lawn Mower Technology, Lawn Mower SafetyLawn MowingLawn CareMowing your lawn.


Hello everyone, My name is Richa and I am here to make you a better gardener by creating an in-depth and helpful resource for all the fellow gardeners out there. If I could help even a few people understand their plants better then I call it a success for my efforts.

2 thoughts on “Why Is My Lawn Mower Spark Plug Wet? (3 Possible Problems+Fix)

  1. I don’t think the title of your article matches the content lol. Just kidding, mainly because I had some doubts after reading the article.

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