Water In Gas Lawn Mower: Signs, Reasons, and Fixes

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By Kirsi Jansa

Water contamination in the fuel of a lawn mower can lead to several issues, compromising its efficiency and functionality. The presence of water can cause the engine to sputter or stall, as it inhibits the proper combustion of the fuel. Over time, water in the gas can also lead to corrosion of the internal components, diminishing the lifespan and performance of the lawn mower. Additionally, it may clog the fuel lines and carburetor, necessitating more frequent maintenance and repairs.

Fix Lawn Mower With Water In Gas

Signs that Show Water is in Your Gas Mower

Difficulty Starting

Water in the gas can make a mower hard to start as it disrupts the normal fuel combustion process. The engine might require multiple attempts to ignite, and the mower may need more pulls on the starting cord or key turns than usual.

Sputtering or Stalling

If the mower’s engine sputters or stalls, it could indicate the presence of water in the gas. Water does not burn like gasoline and interrupts the smooth operation of the engine, leading to irregular performance and unexpected stops.

Power Loss

Water-contaminated fuel can cause a significant loss in engine power. The mower might struggle to cut grass efficiently and exhibit sluggishness or require more effort to push, especially through thick or tall grass.

Visible Water in the Fuel Tank

If you see separated layers of liquid in the fuel tank, it’s a clear sign of water contamination. Gasoline and water do not mix, with water typically settling at the bottom due to its higher density.

Corrosion of Internal Components

Over time, the presence of water can lead to corrosion within the fuel system and engine. Rust or corrosion on spark plugs, fuel lines, or carburetor components indicates water contamination.

White Smoke

If the lawn mower emits white smoke from the exhaust, it could indicate that water is in the gas. This occurs as the water turns to steam during combustion and is expelled through the exhaust system.

Signs that Show Water is in Your Gas Mower

Fixing a Lawn Mower with Water: Step-by-Step Guide

Step 1: Empty the Fuel Tank

Start by safely emptying the fuel tank of the contaminated gas. Ensure that the mower is off and cool to the touch. Use a hand pump or siphon to remove the gas into an approved container. Dispose of the contaminated fuel responsibly at a local hazardous waste facility.

Step 2: Clean the Fuel Tank

Once emptied, clean the inside of the fuel tank thoroughly. Swab it using clean, absorbent rags to remove any remaining water or residue. Leave the fuel cap off for a while to allow the tank to air-dry completely before refilling.

Step 3: Replace the Fuel Filter

Water in the gas can clog the fuel filter with impurities. To ensure smooth operation, replace the fuel filter according to the mower’s manual. This will prevent any remaining contaminants from entering the engine.

Step 4: Check and Clean the Carburetor

Inspect the carburetor for signs of water damage or corrosion. Clean it using a carburetor by spraying it into the components and wiping away residue. This step is crucial as the carburetor regulates fuel flow into the engine.

Step 5: Refill with Fresh Gasoline

After cleaning and replacing the necessary components, refill the tank with fresh, high-quality gasoline. Ensure the gas is clean and stored correctly to avoid reintroducing water.

Step 6: Check the Spark Plug

Water contamination can affect the spark plug, so inspect it for corrosion or fouling. Clean it with a wire brush or replace it if necessary, ensuring a strong ignition spark.

Step 7: Test the Mower

Finally, test the lawn mower by starting it up. Allow it to run for a few minutes and observe its operation closely. Listen for irregular sounds and monitor its performance to ensure all issues have been resolved.

Step 8: Regular Maintenance

After fixing the mower, adopt regular maintenance practices. Check the fuel and other fluid levels regularly, keep the mower clean, and store it in a dry place to prevent future occurrences of water contamination.

Reasons Water Occurs in Gas Lawn Mowers

Condensation: Water can enter the fuel tank due to condensation forming inside the tank, especially when the mower is stored in a place with fluctuating temperatures.

Contaminated Fuel: Filling the mower with gas that already contains water, often due to being stored in a contaminated container or purchased from a contaminated source, leads to water in the fuel tank.

Rain or Spills: Leaving the gas cap off or loose or spilling water around the filler neck while washing can allow water to enter the fuel tank, particularly during rain or cleaning.

Faulty Seals or Gaskets: Damaged or deteriorating seals, gaskets, or fuel caps can allow water ingress, especially if the mower is exposed to wet conditions or high humidity.

Improper Storage: Storing the lawn mower in damp or humid conditions without proper ventilation can facilitate water accumulation inside the fuel tank over time.

Tips to Avoid Water Contamination in Gas Lawn Mowers

Use Quality Fuel: Always use fresh and high-quality gasoline from a reputable source to avoid introducing water-contaminated fuel into the mower.

Tighten Gas Cap: Ensure the gas cap is securely tightened after refilling to prevent water ingress, especially during rain or cleaning.

Store in a Dry Place: Keep the lawn mower in a dry, well-ventilated area to minimize condensation and exposure to moisture.

Regular Maintenance: Perform regular maintenance checks, paying attention to the fuel tank, seals, and gaskets to identify and rectify potential water ingress points.

Use a Fuel Stabilizer: Adding a fuel stabilizer to the gas can help absorb moisture and reduce the risk of water contamination, especially during long storage periods.

Avoid Old Fuel Containers: Refrain from using old or contaminated fuel containers to store gasoline, as they may have accumulated water over time.

Check Weather Seals: Regularly inspect and replace any worn or damaged weather seals or gaskets around the fuel tank and cap to prevent water from seeping in.

Tips to Avoid Water Contamination in Gas Lawn Mowers

Frequently Asked Questions

Why is my lawn mower’s engine oil milky?

Milky engine oil in your lawn mower is typically a sign of water contamination, likely due to a compromised seal, gasket, or prolonged exposure to high humidity or water, which allows water to mix with the oil.

How to clean a water-affected oil reservoir in my lawn mower?

To clean a water-affected oil reservoir, drain the milky oil completely, replace it with fresh oil, and change the oil filter. Running the engine briefly with the fresh oil will help remove any remaining contaminated oil from the system.

Can fuel stabilizers lead to water contamination in the gas tank?

No, a fuel stabilizer is designed to protect the fuel against degradation and oxidation and help absorb moisture, thereby reducing the risk of water contamination in the gas tank, especially during storage.

How weather affects lawn mowers?

Weather can significantly affect lawn mowers; extreme temperatures can lead to fuel degradation and battery issues, while humidity and rain can contribute to rusting, corrosion, and water contamination in the fuel and oil.

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