Water in Gas Lawn Mower: Why + How to Get it Out

A lawn mower engine runs purely on gasoline. Water getting into a lawn mower can result in various problems like the engine not starting, the lawn mower sputtering, and severe damage to the fuel system. So how can water get into a lawn mower?

Water in a lawn mower gas tank can result from using a fuel that contains a high amount of ethanol. Keeping the lawn mower out in rain or damp places also exposes it to moisture-related problems.

Water in Lawn Mower Gas Tank?

There are several ways through which water can get into lawn mower gas tank:

Using Fuel Containing Ethanol

Using fuel containing ethanol can result in water in a lawn mower gas tank. Ethanol draws moisture from the air which condenses inside the fuel tank to form water. It usually happens in winter break when you fail to empty the lawn mower fuel tank or add a fuel stabilizer.

Upon longer storage, fuel can also degrade and cause serious problems. The gas evaporates leaving behind sticky substances that clog fuel filters, fuel lines, and the carburetor.

Keeping Lawn Mower Out in Rain

It is advisable to store your lawn mower in a well-ventilated dry place. A lawn mower getting rained on can result in water getting into the gas tank especially when the gas cap is loosely fitted or is having some cracks and small openings.

Improper storage of a lawn mower

Water can enter the fuel tank through condensation if you store the lawn mower in a dump and humid locations. This process usually creates a vacuum that pulls in moist air into the fuel tank. It condenses into water and settles at the bottom of the gas tank.

How to tell if there is Water in Gas Lawn Mower

Contamination of the fuel tank with water can cause severe performance problems. Water or moisture can cause corrosion or rust in the fuel tank and carburetor components. Here is how to tell if there is water in the lawn mower fuel tank:

1. Hard Starting

Cranking the pull cord severally but nothing happens? There are several issues that cause this problem. The lawn mower won’t start if there is water in the gas tank. Water is denser than gas and will sink at the bottom of the fuel tank where intake happens.

Since most lawnmowers are designed to draw fuel from the tank bottom, the mower will draw water first into the carburetor. The water will then be directed into the ignition and combustion chambers of the engine instead of fuel.

2. Poor Engine Performance

Traces of water in the fuel may cause a lawn mower to keep raving up and down. The water may not be enough to stop the engine but it is significant enough to affect performance.

In some cases, the engine may be running but stops when engaged or when increasing the throttle. The only solution to this problem is to drain to empty the mower fuel tank by draining off its content. You’ll also need to clean the carburetor and fuel lines to remove all traces of water.

3. Lawn Mower Starts but Sputters

A small amount of water in the gas tank may not affect the starting of the engine but will result in sputtering. This means that the fuel won’t sustain combustion in the engine. In some cases, the engine may also stall or stop running completely.

4. Excess Smoke from the Engine

The unusual amount of smoke coming out of a lawn mower engine may also indicate the presence of water in the gas tank. This problem can also result from poor fuel combustion in the piston chambers. You can tell so if the smoke is accompanied by a fuel smell.

How to get Water out of Lawn Mower Gas Tank

If you realize the presence of water in the lawn mower fuel tank, it is important to get it out as soon as possible. Here is what you need to do:

1. Take the lawn mower into an open place and assemble the necessary tools

You are basically going to remove the fuel tank, fuel lines, and carburetor from the mower to get rid of the water. Therefore, you will need a safe well-ventilated place and the necessary tools to do the job. Fortunately, you won’t need much, a socket wrench, screwdriver, pliers, and flathead screwdriver are enough.

2. Disconnect the spark plug

For safety purposes, remove the spark plug before doing anything else. Remove the fuel filter and loosen the fuel tank bolts and disconnect it from the mower. Be sure to remove the governor springs by bending them down. The fuel tank should be able to come out with ease.

3. Empty the fuel tank

Empty out all of the contaminated fuel into a container. Remove the primer assembly from the gas tank to access the reservoir that will be containing contaminated fuel. Be sure not to damage the gasket and diaphragm when opening the reservoir for clean-up.

4. Dry the gas tank

Insert a dry piece of cloth into the tank to clean up all the fuel residues at the bottom and sides of the tank. Use a screwdriver to move the rung around every corner of the tank. Use pliers to remove it from the tank when done with the cleaning.

5. Empty the Carburetor bowl and fuel lines

Disassemble the carburetor and empty the carburetor bowl. Use carburetor cleaner to clean all components of the carburetor. Dip a paper towel into carburetor cleaner and wipe thoroughly all around the bowl. When done, reassemble the carburetor.

6. Re-attach fuel lines, carburetor, and fuel tank

When you are done with cleaning, re-attach everything including the fuel lines. Be sure all the bolts are tightly fitted. Fix back the spark plug onto the cylinder.

7. Refill the tank

Refill the tank with fresh gasoline and start the engine. The lawn mower should be able to run smoothly.

Final thoughts

It is always recommended to store your lawn mower in a dry shelter. Add fuel stabilizer if you intend to store it for a longer duration. The problem of water in the gas lawn mower tank should be resolved as soon as possible before it ; leads to severe damage to the engine and its components.

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