How To Drain Gas From Lawn Mower?[Siphon & Non-Siphon Methods]

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By Kirsi Jansa

Draining gas from a lawn mower is important to prevent fuel degradation and the formation of deposits, ensuring smooth operation and longevity of the engine. This practice is especially crucial during long-term storage, as stale fuel can lead to starting problems and costly repairs.

Drain Gas From Lawn Mower

Different Methods to Drain Gas for a Lawn Mower

Siphon Method

  • Tools Required: Siphon pump, gas can or container, gloves, goggles, and rags.
  • Difficulty Level: Easy
  • Time Needed: Approximately 30 minutes

Detailed Instructions

Safety Precautions

  • Wear gloves and safety goggles.
  • Work in a well-ventilated area, away from open flames or sparks.
  • Make sure your machine is not hot, and remove the spark plug.

Access Fuel Tank

  • Locate the fuel tank cap on your lawn mower.
  • Remove the cap.
  • Prepare Siphon Pump & Container
  • Place an approved gas container on the ground next to the lawn mower.
  • Insert the siphon pump’s suction tube into the lawn mower’s fuel tank.

Start Siphoning

  • Insert the discharge tube of the siphon pump into your gas container.
  • Start pumping (usually by squeezing a bulb or handle) to begin the siphoning process.
  • Continue pumping until the fuel tank is empty.

Manage the Gasoline Properly

  • Safely store the container with the old gasoline.
  • Dispose of it according to local regulations, usually at a hazardous waste disposal site.
  • You can also add a fuel stabilizer to store the gas for as long as possible. Add the stabilizer according to the amount of gas you have. The general rule is one ounce of stabilizer per two gallons.

Clean Up

  • Wipe off any spilled gasoline with rags.
  • Wash hands thoroughly after completing the task.

Run the Mower

  • Run the mower to consume any leftover gas in the fuel tank, pipes, or carburetor. This removes any chance of leftover gas going stale before storage and creating issues.

Siphon Method

Non-Siphon Methods

Fuel Lines

Disconnecting the fuel lines allows you to drain gas directly from the tank. After shutting off the fuel valve and wearing safety gear, carefully detach the fuel line from the carburetor or tank, letting the gas flow into a suitable container.


Utilizing a funnel, you can guide gasoline from the tank to a container. After accessing the fuel tank, insert a funnel into its opening and position a container below it to catch the draining fuel, ensuring minimal spillage.

Tilt and Pour

This method involves tilting the mower and pouring out the gasoline into a container. Ensure the oil cap is tight, disconnect the spark plug for safety, and carefully tilt the mower to direct the fuel out of the tank, avoiding spills.

Run the Mower (Only if the Gas is Fresh)

Running the mower until it uses up all the gasoline is efficient when dealing with fresh fuel. Ensure the mower is in an open area, start it, and let it run until the gas is depleted, avoiding potential fuel storage issues.

Non-Siphon Methods

Safety Tips for Draining Gas from Lawn Mower

  • Work in a Well-Ventilated Area: Ensuring good ventilation reduces the risk of inhaling harmful fumes and prevents the accumulation of combustible vapors.
  • Wear Protective Gear: Gloves and safety goggles protect your skin and eyes from gasoline splashes, which can be irritating and harmful.
  • Avoid Open Flames and Sparks: Work away from any open flame or sources of sparks, as gasoline is highly flammable and can ignite easily.
  • Use Approved Containers: Always use containers approved for gasoline storage to prevent leaks and minimize fire risk.
  • Secure the Mower: Ensure the mower is stable and secure before draining gas to prevent any accidental tipping or spillage.
  • Disconnect the Spark Plug: Disconnecting the spark plug prevents the mower from accidentally starting, which could lead to injuries.
  • Dispose of Gasoline Properly: Safely dispose of drained gasoline at an approved disposal facility to prevent environmental contamination and comply with local regulations.

What happens if you don’t Drain Gas from a Lawn Mower before Storing?

Degradation of Fuel

Over time, gasoline in the mower can degrade and lose its volatility. This breakdown results in the formation of gum and varnish, which can clog the fuel system, leading to difficulties in starting the mower and potential damage to the engine.

Formation of Deposits

The degradation of fuel can also lead to the formation of deposits within the carburetor and fuel lines. These deposits can obstruct fuel flow, impair the efficiency and performance of the mower, and may necessitate extensive cleaning or part replacements.

Ethanol Problems

Many gasolines contain ethanol, which can absorb moisture over time. This can lead to phase separation, where water settles at the bottom of the fuel tank, causing rusting and corrosion and potentially damaging the engine and fuel system components.

Stale Fuel Odor and Inefficiency

Stale fuel develops a sour odor and loses its combustibility, making the engine harder to start and reducing efficiency. Running the engine on old, degraded fuel can result in suboptimal performance and increased emissions.

Increased Repair Costs

Not draining gas before storage increases the likelihood of engine and fuel system issues, leading to potentially higher repair and maintenance costs when you bring the mower out of storage. Regular maintenance, including draining old fuel, helps avoid such unnecessary expenses.

What happens if you don’t Drain Gas from a Lawn Mower before Storing

Frequently Asked Questions

Should I start my lawn mower after draining the gas?

Starting your lawn mower after draining the gas can be beneficial to ensure that any remaining fuel in the carburetor and fuel lines is burned off. However, be cautious and consult your mower’s manual, as running it without fuel can sometimes harm the engine.

How frequently should I drain gas from a lawn mower?

It’s advisable to drain gas from a lawn mower before any prolonged storage period, typically during winter months. Regular seasonal maintenance and using fresh fuel can help maintain the mower’s performance and longevity.

Can I use a fuel stabilizer instead of draining gas before winterizing my lawn mower?

Yes, adding a fuel stabilizer to the gas in your lawn mower before winterizing can prevent fuel degradation and is a good alternative to draining the gas. Follow the stabilizer manufacturer’s instructions for best results.

Can I put drained gas in my car or other engines?

Using drained gas in cars or other engines is generally not recommended, as it might be contaminated or degraded. However, if the gas is fresh and free of debris, mixing it with fresh gasoline in a vehicle’s fuel tank can be a way to repurpose it.

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