How to Get Water Out of a Lawnmower Gas Tank, step by step

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Even when you check the weather forecast or rain radar regularly, it is always possible that you unexpectedly get into a shower. When you quickly get inside, you leave your lawnmower outside, and it will get wet. Usually, this is not a problem, but when water or moisture somehow get into the fuel tank, it is a different story.

It is always suggested to store your lawnmower in a nice safe shelter, so your machine is safe from environmental hazards. Keeping it out in rainy weather or a damp shed may cause it to quit working at some time. If you have forgotten to store your lawnmower after using it, it is exposed to some rainy weather, and it does not start. It can be an indication that water has seeped into the gas tank. To fix this, you have to remove all the water from it.

How to get the water out of a lawnmower gas tank, step by step:

  • Step 1: Diagnose if there is Water in Your Lawnmower
  • Step 2: Disconnect the spark plug
  • Step 3: Siphon the diluted gas
  • Step 4: Dry the tank
  • Step 5: Drain the oil
  • Step 6: Empty the carburetor bowl
  • Step 7: Dispose of all the diluted oil
  • Step 8: Refill the tank
  • Step 9: Use a fuel additive to combat moisture in your tank
How to Get Water Out of a Lawnmower Gas Tank, step by step 1
(CC BY-SA 2.0) by djuggler

Once you have realized that there has been water contamination to your lawnmower’s gas tank, there is no need to panic. The problem is not difficult to fix. Make sure you do not ignore the problem, as it can cause severe damage to your engine. Long term damage to the lawnmower may include corrosion in the tank, fuel lines, and the carburetor.

Water in the lawnmower’s gas tank can be due to it being left out in the open when it was raining, and some rainwater seeped into the gas tank. Another possibility is that your lawnmower is stored in such a warm place during daytime and is cold at night that it makes a partial vacuum that sucks moist air into your tank. There it condenses and settles down at the bottom of the tank.

Although lawnmowers are made waterproof, there is always the chance for accidents like these to take place, particularly when the lawnmower is older.

Get the water out of the lawnmower gas tank in 9 easy steps.

● Step 1: How to diagnose if there is water in your Lawnmower.

The first thing to do is to confirm that your lawnmower has water contamination in its gas tank. If your lawnmower has one (or more) of the following problems after being exposed to rain or a damp environment, there is a high chance it is caused by water in your gas tank:

– Hard Starting

Water is denser than gas, sinks at the bottom of the gas tank, and most of the lawnmowers’ models draw gas from the tank’s bottom. Hence, when you start the lawnmower, the gas tank’s water will go into the carburetor before fuel and cause problems.

– Poor Performance

When the quantity of water in the fuel is not very significant, the engine will start fine. But the water can result in poor performance and will not accelerate like it should when throttled.

– Continuously starting and sputtering

When the water in the fuel tank is in small amounts, the engine will start smoothly, but your mower may suddenly sputter or stall or completely stop running. Often it may yet start again, but the same thing may happen again.

– Fuel System Damage

If you notice any problems in the performance caused by the accumulated water in the lawnmower’s fuel system, check your engine as soon as possible. If you are too late, it may inflict significant damage to your engine. You can protect your lawnmower from any damages such as corrosion or rust over time.

– Smoke coming from the engine

Sometimes you may also notice an unusual amount of smoke coming out from the engine, which can be due to poor combustion in the piston chamber.

● Step 2: Disconnect the spark plug.

The first thing you must do is to remove the spark plug for safety purposes.

● Step 3: Siphon the diluted gas.

The second step is to siphon the diluted gas out of the lawnmower. For this purpose, insert the siphon tube of a hand-pump into the gas tank of the lawnmower. Insert the drain tube of the pump in the container where you will collect the diluted gas. Now pump the device and extract all the gas from the tank.

● Step 4: Dry the tank

Although you have extracted the gas, there may still be a little water attached to the walls inside the tank. So, carefully dry the tank with a dry piece of cloth, or you can also use compressed gas or by spraying it with a WD-40.

● Step 5: Drain the oil.

Now the next step is to drain the oil. Tilt the mower by propping up the front of the mower on blocks. And pun a collecting pan under the machine’s drain plug, which is located at the underside of the mower.

Unscrew the plug with a wrench, and wait for all the oil to drain out into the pan. If there is no drain plug, lift the carburetor from the side on which the air filter or the carburetor is located and pour the oil out from the oil fill hole.

● Step 6: Empty the carburetor bowl

Now empty the carburetor bowl. It is a metal cylinder that is usually located on the side of the mower. Wipe thoroughly all around the bowl with a dampened rag with carburetor cleaner to not let the dirt from falling once it is removed.

Also, place a rag under the bowl to catch the liquid. There will be at least one set bolt present. If you find a second offset bolt, then it is a drain plug.

If there is no drain plug, then unscrew the bolt and pour out the carburetor bowl’s contents.

● Step 7: Dispose of all the diluted oil.

Collect all the diluted gas and the oil and dump them at the local hazardous waste recycling facility.

● Step 8: Refill the tank

Now reconnect the fuel line and refill the tank with fresh gasoline and engine oil.

● Step 9: Use a fuel additive to combat moisture in your tank

If you live in an area where moisture is a problem using a fuel additive could be the right solution. An example of such a fuel additive is HEET. It is specially made to remove water from your gas tank.

This method may be more costly, but if it means you can avoid damage, your lawnmower will be avoiding it is more than worth it.

Note: Make sure that there is more gas than water in your tank. Else the fuel additive will not work. Check the fuel additive manual for more information.

Related Questions:

1) How did the water get into my gas tank when I never left it out in the rain?

Although your lawnmower has never been left out in the rain or may not have been in contact with water, water still enters the gas tank by condensation.

This phenomenon occurs in the winters, usually when you leave your lawnmower in a damp and humid place.

For this issue, you should tightly close the opening of your tank so that no water can seep in. Also, try not to store your lawnmower in such places and try to buy a plastic cover for your lawnmower.

2) Why is my lawnmower oil milky?

If the oil color from your lawnmower is ‘whitish milky,’ then it is contaminated with water. The oil with greenish milky color is because of the presence of antifreeze in it. If the addition of water to the oil is due to condensation of water in the engine, then the milky white color should disappear when you warm the landowner.

3) Are lawn mowers waterproof?

A lawnmower can not be completely waterproof. However, water can still be used to clean your land mowers. Landowners are designed to tolerate a little bit of rain on the lawnmower’s engine.

After the rain, turn on the mower and heat it for a few minutes. The engine’s heat will evaporate the water and clear the moisture, which will protect the motor from the rust.

Final Remarks:

Although your lawnmower may be waterproof, water can still enter your lawnmower’s gas tank (by the causes mentioned above). The best way is to drain out the water contaminated fuel and refill it with the new one. The alternate yet slightly more expensive method is to use the fuel additives. Both of these methods are fine, and you should choose which one fills your needs.

So the best way to avoid this inconvenience is to keep your lawnmower at a dry place in winters. You can also buy a plastic cover to protect it and be sure to close the opening of the tank tightly. Taking serious precautions is better than facing severe damages to your machine or following a rigorous step to fix it.