Bad gas in lawnmowers is a dangerous concept, because it may cause your equipment to fail or cause headaches with the repairs.

Bad Gas in Lawn Mower

There are a few symptoms that may help you determine early on whether your lawn mower has bad gas in its fuel tank or not.

As you read on, you will find that we have compiled a list of the problems you may face once when dealing with bad gas.

What Does Bad Gas In Your Lawn Mower Cause?

Bad gas in your lawn mower causes engine problems, and the machine would be stalling. It would also decrease the fuel efficiency, and you would have difficulties starting it. Lastly, it would also decrease the lifespan of the lawn mower. 

You may see your lawn mower performing below its potential. Several reasons can cause that, and you’ll know you’re dealing with low-quality fuel in your lawn mower if you’re facing some of these issues problems.

Bad Gas in Your Lawn Mower Cause

The results would have a devastating effect on you if you keep the bad gas for a prolonged period of time. 

– Engine Problems

A poorly running engine is one of the biggest problems you can face, and this is why your engine will have problems running smoothly. You will quickly notice that the revs will continuously increase and decrease even when the engine is idling. The machine’s running would be a little shaken, and you would even feel it trembling, due to the irregularity of the gas. 

Suppose the gasoline has been stored for a long time. In that case, it can deteriorate and form deposits in the engine, clogging the fuel system and damaging the carburetor, fuel injectors, or other components. Bad-quality gasoline in your lawn mower’s gas tank can also contain contaminants, such as water or acids, which can cause corrosion in the engine and damage its components.

On another note, if the gasoline has a low octane rating, it can cause engine knock, a condition in which the fuel burns too quickly, causing the engine to produce knocking or pinging sounds. This can cause damage to the engine’s cylinders, pistons, and other internal components. So ultimately, this can lead to reduced performance, increased emissions, decreased fuel efficiency, and reduced engine lifespan. 

– Stalling

Another problem you might need help with is stalling your lawn mower. When the engine is incapable of proper fuel combustion, it stalls, causing even further trouble when trying to restart the engine. Obstruction can occur if the lawn mower’s engine is supplied with gasoline with a low octane rating or has gone stale, but this is due to the low-quality fuel that can cause engine misfires, which may cause the engine to stall.

This can be particularly problematic if the mower is used to cut grass, as a stalled engine can cause the mower to stop suddenly and potentially damage the lawn. To prevent stalling, use fresh gasoline with an octane rating appropriate for the mower’s engine and avoid storing gasoline for long periods.

– Decreased Fuel Efficiency

Using bad gas in a lawn mower can make the engine use more fuel and perform worse. This happens because the gas can cause clogs in the engine’s fuel system, cause knocking sounds, or have harmful contaminants. Using fresh gas with the right octane rating can help the engine run better and use less fuel.

Using fresh gasoline with the right octane rating and avoiding storing gasoline for extended periods will help ensure that the engine in the lawn mower is supplied with high-quality fuel that is free of contaminants. On the other hand, this isn’t the case for the matter, because the machine with some bad gas has gone through a malfunctioning state, where the fuel efficiency has been shaken. 

– Difficulty Starting

Using bad fuel can also cause the engine to become flooded, making it difficult to start. Flooding occurs when too much fuel is present in the engine; this is why the spark plug will see some challenges in order to ignite the fuel and to start the engine.

Basically, it doesn’t have the right power to give itself a proper power source. 

– Reduced Engine Lifespan

If gasoline is not fresh and has been stored for a long time, it can become contaminated with unwanted substances like dirt, rust, or water. These contaminants can cause damage to the important internal engine parts, such as the cylinder walls, bearings, and pistons

Solving Lawn Mowers Bad Gas

These parts work together to keep the engine running smoothly and efficiently, so damage to them can cause serious problems, and eventually, it won’t start. There are a few tests you can run to check whether your fuel is bad or not.

How To Solve The Problem 

To solve a bad gas problem in lawnmowers, you should place some fresh gasoline, or check the quality of the gas before buying it. You should also avoid storing the gasoline for a long time, make sure you would drain the old one, and even clean the system. 

– Fresh Gasoline

Using fresh gasoline is one of the key steps in preventing problems caused by using low-quality fuel in your mower. Fresh gasoline contains high-quality fuel free of contaminants, which can help ensure the engine runs smoothly and efficiently. To begin with, this is the type that you can invest in and fill your machine with when you first buy it and continue to do so in the long run.

Moreover, when purchasing gasoline, choosing an appropriate octane rating for your mower’s engine is important. Check the owner’s manual or the engine manufacturer’s website for the recommended octane rating. The latter will help your mower to run smoothly and keep it from breaking down, because the company is giving you a recommendation, and they wouldn’t want to harm the experience of the machine. 

To ensure you use good gasoline, check the manual for your mower or the engine maker’s website for the best gasoline. Using fresh, good gasoline can prevent problems like difficulty starting, poor performance, and engine damage. This will help your mower last longer and work better for you, and it will increase the life quality. 

– Check The Quality Before Buying

This test is a simple and quick way to check whether your fuel is of good quality, which is what you should do before you would buy it. Fuel that has gone bad has a strong, pungent odor. If the gasoline in your mower smells sour, it has likely gone bad and should be drained and replaced with fresh fuel

Of course, this test is not a foolproof way to determine the quality of the gasoline, but it is a good starting point for checking if the fuel needs to be replaced. On another note, if you are still determining the fuel quality in your mower, it is always a good idea to drain the old gasoline and add fresh fuel to help ensure optimal performance and prevent problems from occurring.

Another way to test it would be to check the color of the gasoline in the tank to determine fuel quality. Clear or light yellow is good, while dark or murky color with particles may mean bad or contaminated fuel. What you should do is to replace low-quality fuel to avoid engine problems and ensure smooth running.

– Avoid Storing Gasoline

Store gasoline in a clean, sealed container that is not near heat or sunlight. If there’s extra gas, use it immediately or drain it before putting your mower away. This helps keep the gas fresh whenever you are going to place it again, and it would keep the machine’s lifespan quite longer.

It is important to store gasoline only for a short time. Note that the latter will help keep the gasoline fresh and free from things like dirt, rust, or water that can cause problems for the engine. When you use fresh gasoline, the engine will run smoothly and efficiently.

It will also prevent issues like difficulty starting, decreased fuel efficiency, engine wear and tear, and other problems. Avoiding storing gasoline for long periods will help ensure that your engine runs well and provides reliable performance.

– Draining Old Fuel

Draining old gasoline from the engine and adding fresh gasoline can help solve problems caused by using low-quality fuel. Remember that when you have some old gasoline, it can contain contaminants such as dirt, rust, or water, which can cause damage to the engine’s internal components and lead to issues like difficulty starting, decreased fuel efficiency, and engine wear and tear.

By draining the old one and adding a fresh one, you can guarantee that the engine is supplied with high-quality fuel free of contaminants. This allows the engine to run more efficiently and smoothly, helping to prevent problems and extend the engine’s lifespan.

– Cleaning The System

Cleaning the fuel system of a lawn mower can help solve problems caused by using low-quality fuel. The fuel system includes the fuel tank, carburetor, fuel lines, and fuel filter. When you do so, you are avoiding any harm to come towards the machine’s engine. 

Over time, the fuel system can become contaminated with dirt, rust, and other particles, which can cause clogging and decreased performance. Draining the old gasoline and cleaning the fuel system can help remove these contaminants and restore the engine’s performance.

This can be done by running a cleaning solution through the fuel system or using a specialized cleaning product designed to clean a lawn mower’s fuel system. Regular cleaning of the fuel system can help prevent problems caused by low-quality fuel and keep the engine running smoothly.

Checking if The Fuel Needs to Be Replaced


When you have bad gasoline, it would cause different issues to your lawn mower, which is why you should be detailed on different ways to avoid such issues.

So before ending the discussion, let’s look at a little summary of everything mentioned above:

  • If you start seeing symptoms such as having problems starting your mower’s engine, engine knocking, corrosion of your lawn equipment, or the engine stalling, that might be a case of bad quality fuel in your mower.
  • Make sure to use good-quality fuel in your mower’s engine to avoid performance issues and increase the life span of your engine.
  • Perform the tests to check fuel quality if you face issues with your mower.

Now, you know about the problems caused by the usage of low-quality fuel and how to solve those problems.

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