How To Clean Lawn Mower Gas Tank

How To Clean Lawn Mower Gas Tank? Step-By-Step

6 minutes

If you’re looking to improve the aesthetic of your yard, but haven’t used your lawn mower in a while, you might find that it’s not working. This is actually normal and can happen when fuel is left in the gas tank for an extended period of time, as gasoline can block the fuel line if it is left for more than 30 days.

There’s no need to panic if this happens. The simple solution is most likely that you need to clean the lawn mower gas tank before tending to your yard.

In this article, we will outline everything you need to know about how to clean a lawn mower gas tank. 

Let’s get into it!

How To Clean Lawn Mower Gas Tank

If you’re not sure how to do it, cleaning the lawn mower’s gas tank can be a hectic procedure. In this article we will provide a step-by-step process that’s clear and easy to follow. 

Step 1: Inspect & Remove The Spark Plug

A spark plug is usually located on the back or side of a lawn mower engine. It is a short wired cylindrical protrusion, around 1/4 inch thick. 

A spark plug ignites the mixture of air and fuel, and essentially, keeps the engine running. It’s important to note that this can be damaged if there is any carbon build up over the time. 

You can manually inspect any such carbon build up or damage; to do this, use an ignition tester. Without removing the spark plug, this tool can be used to check the ignition spark. The instrument is designed specifically for measuring ignition voltage. 

This will clearly indicate whether your spark plug is functioning. If not, you will need to change it before going any further. 

Once you’ve checked the spark plug, remove it from the engine, this step is absolutely essential for your safety. Leftover gas can start the engine if the spark plug is still attached while you’re cleaning. The rotating blades are extremely sharp and could cause a severe injury. 

Step 2: Drain The Gas Tank 

Always use a regular gasoline container to drain the gas safely. This container should be kept under the gas tank before unplugging the gas line.

Make sure that the clamp between the gas line and the engine is tightly sealed. Once this is secure, allow the fuel from the tank to drain into the gas container. 

At this point, use a flashlight to check the tank and confirm that there aren’t any holes, cracks, debris or rust. If you find any such things, you may need to replace the tank, depending on its condition. 

How To Clean Lawn Mower Gas Tank

Step 3: Clean The Tank

To clean the tank, use a cleaner to spray the inside of the gas tank, as well as the outtake holes. This will help to remove any residual condensation or debris and ultimately, just clean the tank.

Residual condensation can create corrosion inside the tank which can lead to engine failure. 

Step 4: Clean The Carburetor

Any congestion in the carburetor will create obstacles for supplying a sufficient amount of fuel to run the engine efficiently. 

Before starting to clean the carburetor, you will need to do the following:

  1. Remove the engine’s exterior case and check the air filters
  2. Remove the carburetor from the fuel line, clean the screws of the carburetor
  3. You may need to replace the needles of the carburetor, as well as the central gasket; both of their functions will reduce over the time.

The central gasket separates the cylinder head from the engine block, and acts as a regulator in gasoline-powered lawn mower engines.

This is good practice and an important step, replacing those will relieve any future stress. 

Use a specific carb spray cleaner to clean the carburetor thoroughly. Check everything is working properly, then reassemble and reattach the parts. 

Step 5: Rinse The Gas Tank

To rinse the gas tank, you always need to use gasoline. Don’t try to rinse the tank with water, as you won’t be able to remove every drop of water you are putting into the tank. As a result, the residual water will damage the carburetor, the spark plug, and even the needles. 

Pour a small amount of gas into the tank. Seal the tank and shake it vigorously to allow the gas to reach all inside areas. It’s important to note, do not use old gasoline that has come out from the tanker. This will actually clog the tanker even more. 

If you have a metal tank, then it’s most likely that it will have rust in it. To clean the rust, use the following two techniques: acetone cleaner or small rocks. 

To clean with acetone cleaner: 

  • pour some acetone into the tank 
  • shake it as mentioned above
  • then pour out the cleaner 

To clean with rocks:

  • choose some small sized rock
  • Put them inside the tank
  • Add a small amount of gasoline or kerosene with these
  • Then shake the tank side to side

Your metal tank should be clean at this stage. 

Step 6: Inspect The Fuel Filter & Fuel Lines 

Fuel filters provide protection by filtering debris, dirt, or any insects caught in the fuel line. If the filter comes into contact with bad fuel, it may become blocked and stop functioning correctly. We would suggest changing the fuel filter once a year. 

Furthermore, don’t forget to check the fuel line. If it is dry or has any cracks, you will need to change it. 

Step 7: Reattach The Gas Tank

The next step is to reattach the gas tank. Always ensure that you are putting every item back together. It’s a good idea to take photos on your phone in order to remember which part goes where. 

Step 8: Fill Up The Tank

The last step is to fill the tank with fuel. Fill the tank with new fuel instead of using anything old; old fuel could be where the problem originated. Pouring the old fuel will ruin all the work you just put in. 

Always check the fuel level, too high of a fuel level will absolutely harm your tank. 

Maintenance Of  Lawn Mower Gas Tank

It is not always necessary to clean your gas tank, the above steps are only necessary if you haven’t used it for more than a few months, or if the mower is not functioning well.

To keep the tank long lasting without any issues, we recommend always using fresh fuel and keeping the fuel at the recommended level. To achieve the right fuel level, slowly and steadily pour in the oil, stopping just before the “full” mark on the dipstick or the tip of the oil filling hole.

You may also use a fuel stabilizer which will help to keep your fuel in a good condition for longer. 

Additionally, always keep the carburetor clean and repair it if necessary; change the fuel filter, spark plug, and gastek once a year. 


Hopefully reading this article on ‘how to clean lawn mower gas tanks’ has outlined the information you were looking for. Don’t forget to have a look at the instructions provided by the manufacturer, this can be extremely helpful as well. 

Remember to take the necessary safety measures before jumping into the process. Dispose of any old fuel and acetone cleaner in the correct manner, as any negligence can cause an accidental fire or health injury. 

Todd L Miles
Lawn Mowers Enthusiast
I started "Landscape and Lawns Care" to provide clients with lawn care with better service, better products and, most importantly, better ethics. My promise to every customer is to give the greenest grass possible while controlling weeds, insects, and diseases! The most important thing is that I strive to always do the right thing for you, your lawn and your wallet!