10 Reasons Your Lawn Mower Is Not Cutting Well (+Quick Fix)

If your lawn mower is not cutting the grass as it used to do when it was brand new, there might be various issues with its components. So, you will need to identify and fix those before it gets too late. 

Damaged blades, dirty air filters, incorrect cutting height, and poor engine maintenance are some of the most prominent reasons your lawn mower is not cutting the grass well. To fix the problem, inspect the blades, engine, and other parts to ensure they run well. Also, Change any damaged parts.

In this article, I will discuss all the reasons in detail and provide quick fixes for each issue. So stay with us and keep reading for all you need to know about why your mower is not cutting the grass properly. 

overgrown lawn 2

1) The blades are damaged. 

If your lawn mower’s blades are damaged, you will not get the desired output.  

Your lawn can still look clumsy after mowing.  

If you have used your mower for a long time and have not paid attention to its blades, the blades would likely have worn out. 

Many objects like stones and pebbles come in the way of the spinning blades, which can blunt their sharpness. 

So, to have a healthy lawn, your lawn mower’s blades should be sharp enough. 

How to fix it? 

It is recommended to replace the blades once a year, but if you sharpen them regularly, they will last long. 

If you plan to sharpen the blades, necessary precautions must be taken. 

For example, disconnecting the spark plug and wearing protective gear. 

Also read:

2) Clogged or dirty spark plug 

Lawn mower spark plug fix

If the spark plug is dirty or clogged engine will start operating roughly, and the power will be reduced. 

Cutting the grass will be difficult if this issue occurs. 

You might wonder why this is happening if you are unaware that your spark plug is dirty or getting clogged. 

Because of this issue, your mower can even use more fuel. 

How to fix it? 

The spark plug gets dirty if the engine sits idle for a long time. 

Old fuel can also be a reason for the spark plug to be dirty and clogged. 

I will also recommend starting the season with a new spark plug and fresh fuel. 

If your spark plug is not in very bad condition and you think cleaning will solve the problem, then you can clean it with a wire brush. 

Use a spray cleaner and then brush it off with the wire brush. 

If you think the spark plug is too bad to clean and cleaning will not fix the issue, you should replace it immediately. 

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

3) Dirty air filter 

Lawn mower repair 3

A dirty air filter can be another reason for the bad performance of your lawn mower. 

If the air filter I dirty and clogged, the engine will not run properly, and the mower will not be able to cut the grass efficiently. 

A dirty air filter will also cause the engine to heat quickly and lead to fire hazards. 

If you are not changing the air filter every season, it can be very costly if your engine sits down due to the dirt and clogging.  

How to fix this? 

After every 25 hours of use of your mower, you will need to clean the form pre-cleaner. 

The air filter needs to be replaced every season. 

I will recommend starting the season with a new air filter. 

You can also change the air filter if your mower has been used for more than 300 hours. 

Also read: Can You Run A Lawn Mower Without An Air Filter?

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4) Low fuel level 

Lawn mower gas refill

If the fuel level is low in your lawn mower, it can damage your mower, and it will not run properly. 

Low oil levels can be another reason your mower cannot cut the grass properly. 

If the engine is making too much noise, overheating, or the smoke emission is high, the reason can be the oil level. 

Eventually, your mower will stop running, and it won’t even be able to cut the grass. 

How to fix this? 

If you find the above signs, you will need to check the fuel in your mower. 

If the fuel is less, you will need to add fresh fuel to the mower. 

Adding the fuel will fix the issue, but your engine can be severely damaged if you do not detect this on time.  

I usually check the fuel tank before starting the mower. 

You can also practice checking the fuel tank before starting the mower every time, which will make your life easier. 

Also read:

5) Incorrect cutting height 

Lawn mower fixing blade

If the mower’s cutting height is too low or too high, your lawn will not look good. 

It is recommended to keep the grass blades over at least 2.5 to 3 inches.  

If you set the mower at a very low height, the grass will be too short, and if you are setting it too high, the grass will be too long, and the mower will not be able to cut it properly.  

What should be the correct height? 

The correct grass height recommended for a healthy lawn Is 2.5 to 3 inches. 

You can set the blades at three inches in height, then the cutting will take place properly, and your lawn will also look good. 

Then a healthy lawn, you will also need to cut the grass regularly. 

This way, you will not need to take off a lot of length at once. 

This will also save you energy and time if you regularly mow your lawn at 3 inches in height.  

You can start mowing your lawn once the grass grows up to 6 or 7 inches. 

6) The fuel filter of the mower is dirty or clogged. 

lawn mower fuel filter

The fuel filter is present in the fuel line of the mower’s fuel tank. 

It prevents dirt and debris from entering the fuel chamber.

If it gets blocked, the fuel supply will not be sufficient for the combustion chamber. 

This can cause problems for your mower, and the engine might splutter.

It can cause problems while cutting the grass because your mower will slow down, and the engine will run inefficiently. 

A bad fuel filter can also cause your lawn mower to stop. 

How to fix it? 

The first and foremost thing you need to take care of is the maintenance of your lawn mower. 

If you are maintaining it properly, this issue will not occur, and maintenance is a preventive measure. 

If the filter is blocked and clogged, you must locate it and then clean it with a cleaning spray. 

Make sure that the spray remains away from the fuel. 

Place the filter again in the fuel line after you have cleaned it. 

You will need to replace it if it is in really bad condition. 

7) Bent or damaged mower deck 

Lawn mower blade removal

If your mower is cutting the grass unevenly and it is visible to you, the mower’s deck might be bent or damaged. 

The blades of your mower will not rotate at a uniform height if the deck is broken or bent, which is why the grass cutting will not be done evenly or properly. 

How to fix this? 

You will need to check the blades if both the blades of the mower are at the same level and if they are rotating evenly. 

If the blades are not at an even height and both the blades rotate differently, then the deck is bent or broken. 

Check where it is broken or bent. 

Once you find out the problem area, try fixing it with tools. 

If you think you can’t fix it, seek the help of a professional. 

8) Lack of power or poor engine performance 

Lawn mower engine repair 3

There can be various reasons for poor engine performance and lack of power. 

The most common reasons are clogged air filters, fuel filters, damaged spark plugs, stale gas, etc. 

We have already discussed these issues above, and the engine performance can go down due to these issues. 

This is why the mower cannot cut the grass efficiently. 

If your mower lacks power, you can check for any of these issues. 

How to fix this? 

Once you find out the problem after inspection, you can follow the required troubleshooting method, which is mentioned above in this article. 

If you cannot determine why the engine performance has gone down, you will need to seek professional help to fix this. 

Also read:

9) A damaged drive belt 

Lawn mower blade cleaning

If there are too many grass clippings on your lawn mowers deck and it has not been cleaned for a long time, chances are that the drive belt will be damaged. 

This can cause uneven grass cutting and make your lawn look dull. 

Too many grass clippings can break the belt if not cleaned on time. 

How to fix this? 

This issue can be fixed easily. 

You must clean the mower deck regularly and ensure no grass clippings. 

When using your mower, it is important to clean the deck. 

If you see that the drive belt is completely broken, you can look for a replacement. 

10) Lack of service and maintenance 

Lawn mower service 2

If your mower is not maintained properly and the servicing is not done regularly, it is likely that the mower’s performance will go down. 

If this happens, it is obvious that the more will not be able to cut the grass properly, and your lawn will not look healthy. 

What to do? 

You can use the service provided by the mower company.  

You can also do the basic cleaning and maintenance by yourself. 

For example, cleaning the grass clippings and the air filter and oil filter regularly. 

If required, you can change the air and gas filters and mower blades every season.

Final thoughts 

If you are a house owner who uses a lawn mower, you need to focus on its maintenance. A mower can easily break down if not taken properly care of.  

So, if your mower is not cutting the grass properly, it is high time you diagnose the problem and sort it out before it completely shuts down.

In this article, I mentioned all the reasons for your mower not cutting the grass properly. You will also find all the quick fixes for the issue here. But seeking professional help is a good idea if you cannot fix it yourself. 

Why is my lawn mower hard to start but running well? 

This can happen if the carburetor is dirty or the air filter is blocked. So, you will need to check these and do the cleaning to fix this. 

Why is a riding lawn mower not starting and not even making a clicking sound? 

This can happen if the battery has gone completely flat. You will need to check the battery if your mower is not even making a clicking sound. 

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.

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