How to Clean a Lawn Mower Gas Tank

A gas tank is an integral part of your lawn mower. It provides the gas that powers the engine and turns the blade, which can cut through dirt, grass, or anything else you want to mulch into a nice pile for you to tidy up. However, gas tanks are notoriously hard to clean because they’re made of metal and varnish builds up over time due to gas vapors. This guide will show how easy it is to remove this build-up so you can use your lawn mower for years instead of just one season!

How to Clean a Gas Tank That Has Been Sitting?

Cleaning gas tanks that have been sitting can be difficult because gas vapors tend to settle on the bottom of the container and evaporate over time. The first step is simple: clean as normal using 50/50 gas and oil mix. If black flakes do not come out, then the gas tank has been sufficiently cleaned and you can skip to filling with gas again.


If the gas in the gas tank is still dirty after cleaning it normally, here are a couple of ideas on how to clean gas tanks that have been sitting:


  • Drain all gasoline from the gas tank and refill with fresh gas.
  • Soak the gas tank in hot water for 30 minutes then scrub it clean.
  • Pour a cleaning product such as Gumout Carburetor & Choke Cleaner or Seafoam Motor Treatment into the gas tank and let it sit overnight. Drain the gas tank, then fill it with fresh gasoline.
  • Disconnect the gas tank and soak it in a cleaning product such as Simple Green or Purple Power.


Let it sit for 30 minutes, then rinse off with water. Reconnect the gas tank and fill with fresh gasoline. Whichever method you choose, make sure to take your time and be careful not to spill gas on yourself or the ground. Always remember to gas up your lawn mower before cleaning the gas tank, and always clean gas tanks in a well-ventilated area. Happy mowing!

How to Clean a Lawn Mower Gas Tank

It is important to finish proper maintenance in your lawn mower often. This will help keep it clean and clear and can prevent some of the other potential issues that will show up along the way. Many people worry that cleaning out the gas tank in the lawn mower will be tough.

But with these simple steps, you can get it done in no time while keeping your lawn mower in the best shape:

How to Clean a Lawn Mower Gas Tank
  1. To start this process, you will need to remove the spark plug lead. Make sure that you secure it somewhere away from the plug. When that is done safely, you will need to disconnect the battery (if the lawn mower comes with one), by removing the negative lead first and then the positive one so it is no longer attached to the lawn mower that you would like to clean out. You do not want these sparks anywhere near the gas when you do the work through the other steps so make sure it is all unplugged before you start. 
  2. With the spark plug and the battery put safely away from the lawn mower, it is time to move on. You can use something like a fuel line clamp to help seal off the fuel line. You need to do this at the exact spot that it connects over to the carburetor. With this securely in place, you can disconnect the line away from the carburetor, holding the line over a bucket or some other kind of container before releasing the clamp. You can then dispose of all fuel in a manner that is safe. 
  3. It may take a few minutes for the fuel tank to empty. This will depend on how much fuel is in the tank to start with and how big the tank is. When you are certain that the tank is empty, you can grab a flashlight and do a little bit of investigating. You can look for beads of light or debris that will indicate there are some cracks or holes in the fuel tank. 
  4. For some of the loose debris, you should use something like a baster to help remove it. You need to get rid of as much of the debris as possible to help clean out the area and prevent issues with it later. And if you find that there is some damage, it may be time to make a replacement. Only replace the tank with some of the original manufacturer’s equipment to ensure that it fits with your lawn mower well. 
  5. It is important to inspect all parts of the fuel tank to make sure you get it all cleaned out. This includes checking the fuel filter for deposits and for debris to make sure that it is all removed and that nothing can get stuck in the fuel later. If you clean out the tank but forget the fuel filter, you will be right back at the starting point later on. 
  6. Once it is all cleaned up, it is time for you to put it all back together. You can reattach the fuel tank if it is still in a good condition. If there was a lot of damage to the original one, then it is time to install a new tank. Make sure that the cap screws are fastened onto it well so you do not get a big mess later because it can’t hold onto the fuel. 
  7. If you do decide to replace the fuel tank at this time, then you may want to consider replacing a few of the other parts as well. This will help make sure the whole lawn mower is in good working order and you do not need to fix it later. Consider replacing the fuel filter and the fuel line if they are starting to look a little worn down or bad in the process. 

3 Different Gas Tank Cleaners

1. A Metal Brush

Steps To Clean The Gas Tank With A Metal Brush:


  • In order to clean the gas tank, you’ll need a wire brush and some gasoline or gas additive as well as a funnel. Some people prefer using additives because they are more environmentally friendly than spraying things directly into your engine, but it’s up to you.
  • The gas tank needs to be completely dry before starting so make sure it has plenty of time to air out and all the gasoline is gone. Add your preferred gas additive or cleaner to the gas tank, using a funnel if necessary. Shake or stir the gas tank well until the additive is mixed in with the gas.
  • Now you can use your wire brush to remove any rust, gas residue or varnish. Be sure not to damage the metal with too much pressure because it could cause some serious problems down the road. Continue brushing until you are satisfied that all of the gas has been removed from inside and no debris remains in there either.
  • Be aware that this process can take some time, so it’s best to set a day aside for it. However, once you’re done your gas tank will be clean and ready to go!
  • Cleaning the gas tank on your lawn mower is not as daunting as it seems. By following these simple steps, you can have your machine running like new in no time at all.

2. A Garden Hose

There is also another method of cleaning gas tanks that involves using a garden hose and some elbow grease. This process can take a bit more effort but it’s effective if your gas tank has been neglected for years on end. 

  • First, remove the gas cap and set it aside. Then you’ll want to attach a hose leading from your spigot directly into the gas tank opening. Make sure that the gas tank is held in an upright position for this whole process as well.
  • Turn on your water at a slow trickle and allow it to run through the gas tank for a few hours. This will help to loosen any debris or build-up that has accumulated over time. You may need to do this multiple times, depending on how bad the gas tank is clogged up.
  • After you’ve allowed the water to run through, take your hose and spray it directly into all of the nooks and crannies of the gas tank. This will help to dislodge any gunk that is still left inside. Be prepared for it to be a messy process!
  • Once you’ve finished hosing down the gas tank, allow it to dry completely before reattaching the gas cap and using it again. It’s best to store gas cans in a cool, dry place so that gas doesn’t collect and cause rust or other problems.

3. A Carburetor And Choke Cleaner

Steps To Clean The Gas Tank With A Carburetor And Choke Cleaner:


  • Another option for cleaning gas tanks is carb and choke cleaner. This can be found at any large hardware store like Home Depot or Lowe’s.
  • The process of using this cleaner is pretty straightforward. Simply pour it into the gas tank and allow it to soak in for a while. You may need to use a wire brush to help loosen any debris that is stuck inside.
  • Once you’ve allowed the cleaner to work its magic, be sure to flush the gas tank with water several times to get rid of all the chemicals. You don’t want those getting into your engine!
  • Allow the gas tank to dry completely before using it again.
  • No matter which method you choose, always be sure to read the instructions carefully and take all necessary safety precautions. Cleaning a gas tank can be dangerous if not done correctly, so it’s best to be prepared.
  • Now you know how to clean a lawn mower gas tank – regardless of the build-up or debris inside. It may take some time and effort but it will be well worth it in the end!
  • Cleaning a gas tank can seem like a daunting task, but it’s a necessary chore if you want your lawn mower to run like new. By following these simple steps, you can have your machine up and running in no time at all.

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