How to clean a rusty lawnmower gas tank, step by step

Approx Reading Time: 9 minutes

A fuel tank’s fundamental task is to store and supply gas to the engine and ensure that the gas stays clean. If the fuel contains dirt, it can clog the carburetor. This can result in a poorly starting lawnmower and can eventually stop working altogether. A fuel tank that is not a good condition can be a source of dirt and debris that gets mixed with the fuel. Before this can happen, you need to make sure that you clean your fuel tank.

When your lawnmower is older and uses a metal gas tank, one of the more common reasons for clogging the carburetor is rust. When you notice this, you can replace the gas tank or clean it. Cleaning can take some time but will be a lot cheaper than replacing it. This blog will help you with the needed steps to clean a rusty or eroded gas tank yourself.

How to clean a rusty lawnmower gas tank, step by step:

  • Step 1. Make sure that the lawnmower can not accidentally start
  • Step 2. Drain the tank
  • Step 3. Preventively clean the carburetor
  • Step 4. Rinse the tank with different techniques
  • Step 5. Check the fuel filter for deposits, dirt, or debris.
  • Step 6. Close the tank and reattach it
How to clean a rusty lawnmower gas tank, step by step 1
(CC BY 2.0) by rbarnesdotcom

Cleaning a rusty lawnmower tank Step-by-Step:

Cleaning your gas tank is not a difficult task. But before you start with the cleaning, you first should look at some preventive measures. Then we can look into the steps in more detail. What tools do you need, and what is required to finish each step.

● Step 1. Make sure that the lawnmower can not accidentally start

The first step is to make sure that your lawnmower can not start unintentionally. An easy way is to remove the spark plug cables. If there is a little bit of fuel left in the system, this will make sure that the engine can not start while working on it.

Also, make sure that you park the lawnmower in a location with a hard floor capable of dealing with some fuel spill.

● Step 2. Drain the tank

After opening the cap, get prepared with the gas container. Now, remove the fuel line attached to the carburetor. If your lawnmower is liquid fuel operated, drain the fuel into a tank. If it is gas operated, let the air pass out in an open environment. Make sure that you have no source of heat or spark present near it. When the tank is empty, use the flashlight to inspect for dirt, debris, and beads of light that will show cracks or spores. You can use a simple scrapper or blade to remove the slack debris. If you discover the damage in the tank that is too major, stop right there. Either replace it or take it to some expert.

● Step 3. Clean the carburetor thoroughly 

The carburetor is a vital component responsible for the correct air-fuel mixture and leads to the combustion chamber. As it is directly connected to the fuel tank, the dirt and rust from the tank may propagate to its core. Now, if you have opened the machine, cleaning the carburetor is a mandatory step. The clogging or congestion causes the foundation of pipes to thin down, providing inadequate fuel. In extreme cases, the engine power severely reduces and starts making a gurgling or burbling noise.

Cleaning it is simple. Use a pneumatic pump to wipe away the dirt from the insides using strong air pressure. Check the fuel lines, air intake, distributor connected to it; clean them all thoroughly with a petrol wash and air pressure. Make sure that you adjust the right tubes into the right places when you’re done cleaning.

● Step 4. Rinse the tank with different techniques

Now, it is time to get back to the gas tank, especially for the rusty gas tank to be dealt with. Removing the gas tank is pretty simple. You will find 2-3 nut bolts at the bottom. Grease them and remove them carefully. In some lawnmowers, you will have to remove the carburetor first to remove the gas tank. The rust can be removed using the following techniques:

– Abrasive

Abrasive materials are ordinary for confiscating rust from gas tanks. Pea or aquarium gravel and plain gravel are widely used abrasive materials, scrubbing away the rust effectively.

All the gravel must come out of the tank after applying this method. It is recommended to use a liquid like water or an amalgamation of soap and water, which aids the abrasive material and extricates the dust particles.

– Chemicals

Vinegar and baking soda are widely used chemicals. Muriatic acid or isopropyl alcohol is beneficial in loosening the rusty stuff. Using a mixture of abrasives and chemicals can be highly effective for removing rust. You have to ensure that the amalgamation of different substances is compatible not to damage the tank further. In less severe cases, simply using WD-40 will solve your problems.  

– Electrolysis

Carrying out electrolysis to get rid of rust is beneficial for smaller objects; however, it can be used to remove rust from a gas tank with a few amendments. It is significant to practice caution when linking and detaching the power or voltage source, make sure that the ferrous metal is not exposed to the edge of the gas tank. Probably it is better to ask an expert for help with this method.

● Step 5. Examine the fuel filter for dust and deposits

The oil or fuel filter is the final stage before the fuel comes into the combustion process. As the filter’s name suggests, it is responsible for preventing impurities, dirt, and dangerous objects such as insects and residues and let the fuel pass through only. If insufficient or dirty fuel comes in contact, it may become the prime reason for clogged up and lose functionality. In all this, the engine action gets rough, lumpy, and can cause stalling problems.

It is always preferable to use clean fuel with fuel stabilizers when the pressure has to be used. Extra fuel in the tank will still cause problems. Like all filters, the fuel filter should be replaced annually unless the black residue is visible to the naked eye.

● Step 6. Reattach the fuel tank

Fix the old fuel tank properly. Fasten it tightly with the cap screw. Ensure that the connections with the carburetor are proper. Use mild greasing while tightening a nut anywhere. Now it is good to change the filter and fuel line. You may use the liquid fuel you stored. However, add some anti-knocking agents to it, along with fuel stabilizers. Engage the spark plug, and you’re ready to go.

Additional Precautionary actions:

Before starting, operating, or servicing your engine, always read the engine and equipment manual to prevent property damage or personal injury.

  • Protection: Goggles and facemask must be used for protection.
  • Ventilation: It is recommended to work in a well-ventilated area to avoid full exhausts.
  • Chemicals: Mixing products will cause corrosive chemical reactions. So only amalgamate those chemicals, which are defined on the manufacturer’s instructions.
  • Explosion: Ensure that heating and energy sources are far from the area before removing the gas tank.
  • Gas Storage: Gas must be stored appropriately, and keep an extra tank nearby to dilute any chemicals’ spillage.

Frequently asked questions:

1. How do you clean a gas tank that has been sitting?

Fill the tank with water at once. Add a half gallon of muriatic acid into the tank. For a few seconds, shake a tank properly. Make it sit for a minimum of 24-hours so that proper residual vanish out, and you get a clean and clear tank. In doing so, make sure that you have no fuel in the tank and the spark plug has been removed.

2. Does vinegar dissolve rust?

Yes, it can dissolve rust. Persistent rust is best removed by using white vinegar. To dissolve rust is the best way to use acetic acid, which is a familiar domestic product. You can immerse minor things such as earrings or rings, then wipe them onto a rusty surface with some rag or cloth. By just pouring it directly over rust spots will remove the rust. Apply this anti-rust technique on the bolts and screws that have rusted together.

3. How do you clean the inside of an old gas tank?

Remove the fuel pump from the tank and ensure no residual debris or dirt falls into the tank. Attach the hose into the fuel tank and shoot down a stream of hot and clean water. Keep filling the water and at the same time spray mild detergent in the tank. If opening lets, use a brush to loosen dirt, twigs, and debris from the tank’s rims.

Final Remarks:

Learning how to clean rust out of a gas tank will save you time and is cheaper than replacing it. There are several ways to remove rust inside a gas tank. A clean and well-maintained gas tank will help evade the potential negative influences corrosion can cause to your lawnmower. Different approaches, such as abrasives (gravel or washers), acids like muriatic acid or vinegar or, battery and washing soda, are useful to solve the rust issue. You can also use the methods mentioned above in an appropriate mix if the rust problem is severe. In case the rust has left holes in the gas tank, it is better to take it to a professional. You might need to replace it now.