Learning how to drain fuel from lawn mower is a key skill for any homeowner. Draining old fuel from your lawn mower’s tank is a crucial end-of-season task. It prevents starting problems and protects your engine from damage caused by stale gasoline.
This guide provides clear, step-by-step instructions. We will cover several safe and effective methods. You will also learn why this maintenance step is so important for your mower’s longevity.
By the end, you’ll be able to perform this task with confidence. Proper fuel management saves you time and money on repairs.
How To Drain Fuel From Lawn Mower
Before you begin, gather your supplies and prepare your workspace. Safety is the most important consideration when handling gasoline.
You will need a few basic items. Having everything ready makes the process smoother and safer.
- A fuel container approved for gasoline (like a jerry can)
- A length of clear plastic tubing (3/8-inch diameter often works)
- A funnel
- A set of wrenches or a socket set
- Safety glasses and chemical-resistant gloves
- Clean rags or paper towels
- A baking pan or shallow tray to catch drips
Always work in a well-ventilated area, preferably outdoors. Never work near an open flame, spark, or pilot light. Ensure your mower is on a level surface and the engine is completely cool before starting.
Method One: Siphoning The Fuel
Siphoning is the simplest method for most riders and lawn tractors. It does not require any tools to disassemble the mower. This technique uses gravity and suction to remove the fuel.
First, locate the fuel tank cap and remove it. Place your empty fuel container on the ground, lower than the mower’s tank. Insert one end of the clear tubing deep into the mower’s fuel tank.
You need to start the siphon. There are two common ways to do this safely.
Using A Manual Siphon Pump
A small hand-operated siphon pump is a wise investment. It makes this job clean and easy. You simply insert the pump tube into the tank and pump the handle.
The fuel will flow through the tube and into your container. This method gives you good control and minimizes the risk of getting gasoline in your mouth.
The Traditional Siphon Technique
If you don’t have a pump, you can start the siphon manually. Put the other end of the tube in your mouth and give a quick, strong suck. The moment you feel fuel in the tube, quickly lower that end into your fuel container.
Be extreamly careful not to swallow any gasoline. The fuel should now flow continuously from the tank to the can. Once the tank is empty, remove the tube and replace the gas cap.
Method Two: Draining Via The Fuel Line
This method involves disconnecting the fuel line at the carburetor. It is very effective for walk-behind mowers. It allows you to drain the tank and the fuel line completely.
First, locate the carburetor on your mower’s engine. Follow the fuel line from the gas tank to the carburetor. You will see a small clamp securing the line.
Place your drip pan or tray underneath the connection. Use a screwdriver to loosen the hose clamp and carefully pull the fuel line off the carburetor nipple. Point the open end of the line into your fuel container.
If fuel does not flow automatically, you may need to open the tank’s vent (if it has one) or loosen the gas cap to allow air in. Let all the fuel drain out. Once empty, reconnect the fuel line and tighten the clamp securely.
Method Three: Using The Drain Plug
Some lawn mower models, particularly certain riding mowers, have a built-in drain plug at the bottom of the fuel tank. This is the most direct method if your mower is equipped with one.
Consult your owner’s manual to confirm the location of the drain plug. Position your fuel container directly underneath it. Using the appropriate wrench, slowly turn the drain plug counter-clockwise.
Have a rag ready as some fuel may spill when the plug is loosened. Allow all the fuel to drain completely. Once the tank is empty, carefully clean the drain plug threads and reinstall it, tightening it snugly to prevent leaks.
What To Do With The Drained Fuel
You should never pour old gasoline down a drain, onto the ground, or into the trash. It is hazardous waste and must be disposed of properly. Mixing it with fresh fuel is also not recommended for small engines.
Check with your local waste management authority for guidelines. Many communities have household hazardous waste collection days or permanent facilities. Store the old fuel in its clearly labeled container until you can dispose of it safely.
If the fuel is relatively fresh (less than 30 days old) and uncontaminated, you can potentially reuse it in your car. A car’s larger engine and complex fuel system can typically handle slightly older gas better than a small mower engine. However, if the fuel is over a month old or you suspect water contamination, disposal is the best option.
Why Draining Fuel Is Necessary
Gasoline begins to degrade surprisingly quickly. Modern ethanol-blended fuels attract moisture from the air, which leads to seperation and corrosion. This causes several major problems for your lawn mower.
Understanding these issues highlights the importance of this simple task. It is preventative maintenance that protects your investment.
Preventing Varnish And Gum Deposits
As gasoline evaporates and oxidizes, it leaves behind sticky, tar-like residues. These varnish and gum deposits clog the tiny passages in your carburetor and fuel filter.
A clogged carburetor will prevent your engine from getting the right fuel-air mixture. This leads to hard starting, rough running, stalling, and poor performance. Cleaning a carburetor is a much more difficult and expensive repair than simply draining the fuel.
Avoiding Water Contamination And Corrosion
Ethanol in gasoline absorbs water from the atmosphere. Over time, this water can separate and sink to the bottom of your tank. Since water is heavier than gas, it gets sucked into the fuel line first.
Water in the combustion chamber does not burn and can cause the engine to hydro-lock, leading to severe damage. It also promotes rust inside the steel tank and corrosion on aluminum carburetor parts.
Ensuring Easy Starts Next Season
The single most common reason a lawn mower won’t start in the spring is old fuel. Draining the tank or using a fuel stabilizer guarantees you have a fresh start.
You save yourself the frustration of pulling the starter cord repeatedly. Your mower will start quickly and run smoothly when you need it, making your first cut of the season a breeze.
Step-By-Step Annual Fuel System Preparation
For long-term storage, such as over the winter, a full fuel system preparation is ideal. This process goes beyond just draining and ensures every component is protected.
Step 1: Add Fuel Stabilizer (Optional But Recommended)
If you choose not to drain the tank, you must use a fuel stabilizer. Pour the correct amount of stabilizer into the tank *before* adding fresh gasoline. This ensures it mixes thoroughly.
Run the engine for 5-10 minutes to circulate the treated fuel throughout the entire system, including the carburetor. This coats the internal parts and prevents oxidation.
Step 2: Drain Or Run The Engine Dry
You have two choices for the tank itself. You can either drain it completely using one of the methods described above, or you can run the engine until it stops from fuel starvation.
To run it dry, simply disconnect the spark plug wire for safety, then start the mower and let it run until the carburetor and fuel line are empty. This leaves the system dry but may not remove all fuel from the tank.
Step 3: Change The Fuel Filter
If your mower has an in-line fuel filter, this is a good time to replace it. A clogged filter is a common point of failure. Pinch the clamps, remove the old filter, and install a new one in the correct direction (note the flow arrow).
Step 4: Final Storage Steps
Once the fuel system is prepared, complete your winterizing routine. This includes changing the oil, cleaning the mower deck, sharpening the blade, and removing the spark plug to add a small amount of oil into the cylinder.
Store your mower in a clean, dry place. Cover it with a breathable cover to protect it from dust without trapping moisture.
Frequently Asked Questions
How Long Does Gas Last In A Lawn Mower?
Fresh, untreated gasoline with ethanol begins to degrade in as little as 30 days. For reliable performance, do not use gas that is older than one month in your lawn mower. Using a stabilizer can extend this life to 6-12 months for stored fuel.
Can I Leave Gas In My Lawn Mower Over Winter?
It is not recommended. Leaving untreated gasoline in the tank over winter almost always leads to starting problems in the spring. The fuel will break down and likely cause varnish deposits and corrosion. Either drain the tank completely or fill it with fresh gas treated with stabilizer.
What Is The Easiest Way To Get Gas Out Of A Lawn Mower?
For most homeowners, using a manual siphon pump is the easiest and cleanest method. It requires no disassembly, minimizes spill risk, and gives you good control over the process. It’s a simple tool that pays for itself quickly.
How Do You Drain A Lawn Mower Carburetor?
Many carburetors have a small drain screw at the bottom of the float bowl. Place a container underneath, then carefully open the screw with a screwdriver to let the fuel drain out. If there is no drain screw, you can drain the carburetor by disconnecting the fuel line as described in Method Two.
Is It Better To Drain Gas Or Use Stabilizer?
For seasonal storage, draining the fuel system completely is generally the most foolproof method. It eliminates all risk of degradation. Using a high-quality stabilizer in a full tank is an acceptable alternative, especially for newer equipment, but draining is often considered the best practice for long-term engine health.