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How to Siphon Gas from a Lawnmower, step by step

Are you looking to store your lawnmower for winter? Perhaps it might be a good idea to remove all the gas from the tank to choke the fuel lines with its deposits. Or you can have another reason to remove the gas from your lawnmower tank. A siphon pump helps you drain the entire fuel tank without leaving spills all over. If you aren’t sure how to use a hand siphon pump, then try giving this article a read where we demonstrate the procedure for siphoning gas from various types of lawnmowers.

How to siphon gas from a lawnmower, step by step:

  • Step 1: Locate the fuel tank’s cap on your lawnmower. For riding mowers, it is present above the left rear wheel.
  • Step 2: Arrange a plastic container to collect the gas.
  • Step 3: Insert the siphon pump’s top hose into the fuel tank. At the same time, the bottom hose goes into the container for collecting the gas.
  • Step 4: Pump the siphon by hand until all the gas has been drained from the fuel tank.

Some additional methods for gas drainage include:

  • Detaching the fuel line connected to the carburetor and draining the gas from it.
  • For walk-behind mowers, the body can be tilted correctly to drain the gas from the tank.

Gas quality diminishes with time. The chemical compounds in fuel react with the oxygen in the air to form compounds in the form of sticky grey deposits. These deposits can clog the fuel lines along with the filters and the carburetor jets. As a result, you can face difficulty in starting your engine. To prevent this, it is often advised to empty the gas tank whenever you intend to store the mower for long. There are several ways of doing that, and all of them are explained in this blog post.

We recommend reading the full article to get a good understanding of how to siphon gas from your lawnmower along with some other commonly used techniques.

● Siphoning Gas from a Lawnmower, Step-by-Step:

Using a siphon pump is the cleanest and fastest way to extract bad gasoline from the fuel tank. It can be used both for riding lawnmowers and for push lawnmowers. You can buy a siphon pump conveniently by visiting a car parts dealer for as little as $10.

– Riding lawnmowers:

In riding lawnmowers, the gas tank is often located just below the seat. While the cap is on the rear left side. For certain versions, you may need to lift the seat to access the fuel cap.

● Step 1: Insert the hoses in the tank:

To pump the gasoline, open the cap and insert the siphon pump’s top hose so that it is completely submerged in the tank. A siphon pump comprises two hoses. The top hose is placed from where the fuel needs to be drained. The bottom hose, on the other side, brings the drained fuel into a secondary container.

● Step 2: Use a plastic container:

Handle any plastic cylinder or plastic bottle to store the fuel removed from the tank. Avoid using a metal container, as the flow of gas can generate a static charge, which may create a spark in the presence of metal. This condition cannot be afforded since we are dealing with gas.

● Step 3: Siphon the fuel:

Pump the siphon with your hand to drain the fuel from the tank and shift it to the plastic container. Remove any tangles or curls in the siphon hose for quick drainage. Keep siphoning the gasoline until the fuel tank is empty.

-Walk-behind lawnmowers:

The approach is entirely the same for walk-behind lawnmowers, except that the gas tank is easier to identify since it is present externally on the device’s top. Remove the cap and connect the siphon hose to drain the gas.

● Additional Methods for Gasoline Removal:

If a siphon pump isn’t available to you, you can try additional methods to remove gasoline from your lawnmower. These methods involve the manual removal of gas from the tank.

1. Detaching the fuel line:

This method can be applied to both riding and walk-behind lawnmowers. The fuel line that carries gas from the tank to the carburetor is emptied in this method.

– Step 1: Locate the carburetor:

The first step is to locate the carburetor on your lawnmower. For walk-behind mowers, the carburetor is situated right next to the air filter and is visible externally. You need to lift the mower deck for riding mowers and remove the air filter assembly to grasp the carburetor and the engine.

– Step 2: Place the fuel catching container:

Once you have located the carburetor, use a rag to clean the fuel line from any gas. Place a fuel-catching container right underneath the fuel line. After that, use a pair of nose pliers to detach the clamp holding the line and allow the entire gasoline coming from the tank to be collected in the container.

– Step 3: Dispose of the old fuel:

With the tank emptied, dispose of the old gasoline by taking it to an automotive parts dealer. It is also better if you can open your carburetor and clean with WD-40 to remove any deposits formed due to old gas. It might unclog some restricted jets and improve the starting of your engine.

2. Tilting the lawnmower:

Tilting the lawnmower can only be possible in walk-behind mowers since they are compact enough to be tilted. For riding lawnmowers, this method cannot be applied.

– Step 1: Tilt the mower correctly:

The first step is to tilt the mower correctly with the air filter pointing upwards. It ensures that the engine oil doesn’t flow into the fuel lines of the carburetor. Also, remove the spark plug wire as a precautionary measure.

– Step 2: Arrange a container:

With the mower tilted, place a container or a bowl to collect the gas. Open the fuel cap and allow the gasoline to be collected entirely in the container.

– Step 3: Dump the old fuel:

Dispose of the old gasoline in the container. Clean the lawnmower carburetor and reattach the spark plug wire.

● Some Recommendations for better performance:

Once the fuel tank has been emptied, some additional steps should be performed to ensure that old gasoline has been completely removed from the lawnmower.

– Run the mower for a while:

Start your lawnmower’s engine and allow it to run for a while. The engine runs due to some fuel remnants left in the fuel lines and the carburetor. Once the fuel has been consumed, the engine shuts down by itself.

– Clean the carburetor:

It is suggested that if fuel quality has degraded and the tank has been emptied, you should clean the carburetor too. This shall unclog some jets blocked by fuel deposits and improve the engine’s flow of air-fuel charge.

To clean the carburetor, loosen the bowl nut and remove the bowl. Spray a carburetor cleaner liquid on the interiors of the carburetor thoroughly. Spray some fluid on the bowl nut as well. If available, an air compressor spray might also clear some debris formed inside the carburetor. Once cleaned, connect all the parts back and fill the tank with fresh gas. You will notice a much better engine performance after conducting these steps.

Related Questions:

1. What is the best lawnmower gas?

For small engines, some general guidelines regarding ideal gasoline are as follows:

  • The fuel should be unleaded and clean
  • It should have a minimum octane number of 87 or RON of 91.
  • Ideally, it should have 10% ethanol and 15% MTBE (methyl tertiary butyl ether)

2. Do I need to drain the gasoline from my lawnmower?

If you plan to store your lawnmower for long, it is better to drain the gasoline from it. Unused gas left in the fuel tank can get stale with time. It causes choking of the carburetor by forming sticky deposits. It also invites rust. Hence, it is better to drain the fuel tank.

Otherwise, you can add a fuel stabilizer to the tank and allow the mower to run for some time. This running of the engine distributes the fuel stabilizer evenly across the fuel lines and prevents the gasoline from becoming stale.

3. How long does gasoline last with a stabilizer?

Typically, gasoline stabilized with a fuel stabilizer lasts for 1-3 years. However, this only works for fresh fuel. Fuel stabilizers aren’t much effective on fuels whose quality has already been degraded. Or the fuels that have been contaminated with impurities.

4. Will bad gas cause a lawnmower not to start?

Bad quality fuel might have gummed the carburetor and other parts such as the fuel filter itself. First, to start your lawnmower with bad fuel, drain the old fuel from the tank, preferably using a hand siphon.

Once the tank is emptied, clean the carburetor thoroughly using a carb cleaner spray. After that, add fresh fuel to the tank and rerun your engine. If it still doesn’t start, consider replacing the fuel filter.

Some other causes of an engine not starting are:

  • Faulty spark plug
  • Weakened battery
  • Faulty voltage regulator/starter motor in riding lawnmowers
  • Broken flywheel key
  • Insufficient fuel

Final Remarks:

Siphoning the gas from your lawnmower tank can be performed by yourself easily. We strongly advise that while carrying out the fuel drainage, be very careful due to gasoline’s combustible nature. Always perform the drainage in your driveway where electrical connections are far and the sunlight is not directly falling. Lighters, cigarettes, and matchboxes must be kept away. Furthermore, we recommend that the gasoline should be recycled appropriately by taking it to the agent. It is a very good practice to use a fuel stabilizer in your tank as it maintains the fuel quality and prevents you from replenishing the fuel.