How To Remove Gasoline From Lawn Mower

If you’re preparing your lawn mower for storage, knowing how to remove gasoline from lawn mower is an essential skill. Gasoline left in the system over winter can turn into a gummy residue that clogs the carburetor. This simple maintenance task can save you from frustrating starting problems and expensive repairs come spring. This guide will walk you through several safe and effective methods to get the job done right.

There are three primary ways to remove fuel from your mower: siphoning, draining, and running the engine dry. The best method for you depends on your mower’s design and your comfort level. Always work in a well-ventilated area, away from sparks or open flames, and have a proper fuel container ready for the old gasoline.

Gather Your Tools And Safety Equipment

Before you start, collect everything you’ll need. This prevents interruptions and ensures you handle the fuel safely. You won’t need every item for every method, but it’s good to have them on hand.

A approved gasoline storage container
Safety glasses and nitrile gloves
A manual fluid siphon pump or a length of clear tubing
A set of basic wrenches or a socket set
A flat pan or tray to catch drips
A funnel with a fine mesh screen
Clean rags or paper towels
A fuel stabilizer (for fresh gas you plan to keep)

Method 1: Siphoning The Gasoline

Siphoning is often the easiest and cleanest method, especially for mowers without a obvious drain plug. It requires no disassembly and minimal tools.

Step-By-Step Siphoning Instructions

Ensure the mower is on a level surface and the engine is completely cool.
Place your empty gas can on the ground, lower than the mower’s fuel tank.
Insert one end of your siphon pump tube or hose deep into the mower’s fuel tank.
Place the other end into your gas can. If using a manual pump, follow the pump’s instructions to start the flow. For a plain tube, you may need to create suction by mouth (use extreme caution and avoid ingesting fuel) or use a squeeze bulb primer.
Once the fuel begins flowing, allow the tank to empty completely. Gently tilt the mower to get the last bit of fuel from the tank’s corner.
Dispose of the old gasoline properly at a hazardous waste facility or, if it’s fresh, you can reuse it in your car if you mix it with plenty of new gas.

Method 2: Draining Via The Fuel Line Or Tank Plug

Some mowers have a drain plug on the bottom of the fuel tank. Others require you to disconnect the fuel line at the carburetor. This method is very effective but involves a bit more hands-on work.

Draining From The Fuel Line

Locate the fuel line. It’s a small hose running from the gas tank to the carburetor.
Place your drip pan underneath the carburetor area. Use a clamp or a pair of pliers to pinch the fuel line shut near the tank.
Carefully disconnect the fuel line from the carburetor end. You might need to loosen a small clamp.
Direct the open end of the fuel line into your gas can and release the pinch. The fuel should flow out freely.
Once drained, reconnect the fuel line securely to the carburetor.

Using A Tank Drain Plug

If your mower has a drain plug, the process is straightforward. Consult your owner’s manual to confirm its location. Usually, you simply place a pan underneath, unscrew the plug, and let the tank empty. Remember to replace the plug’s seal or gasket if it looks worn to prevent leaks later.

Method 3: Running The Engine Dry

This method uses the mower itself to consume the remaining fuel. It’s simple but doesn’t remove every last drop from the carburetor bowl, which can sometimes be enough to cause issues. It’s best used in conjunction with a fuel stabilizer for the last run.

Take the mower to a well-ventilated outdoor area.
Start the engine and let it run. As it runs, it will use up the gasoline in the tank and the carburetor.
The engine will sputter and then stop once the fuel is gone. Do not try to restart it.
This leaves the fuel system mostly empty, but a small amount may remain in the carburetor’s float bowl.

What To Do After Removing The Gasoline

Simply removing the old gas isn’t the end of the story. To fully protect your mower, you need to address the fuel that remains in the carburetor and prepare the system for storage.

Treat The Carburetor

Even after draining the tank, fuel remains in the carburetor’s small passages and float bowl. This is where it turns to varnish and causes the most clogs.

After draining the tank, restart the engine and let it run until it stops. This will clear most of the fuel from the carburetor jets.
For long-term storage, consider adding a few drops of fogging oil into the spark plug hole or using a carburetor cleaner designed for storage.
As an extra precaution, you can manually remove the carburetor bowl to wipe it clean, but this requires more mechanical skill.

Add Fuel Stabilizer For Seasonal Storage

If you choose not to drain the tank completely, or if you have a small amount of fuel left, a stabilizer is crucial. It prevents the gasoline from breaking down for up to 24 months.

Add the correct amount of fuel stabilizer (like Sta-Bil) to a nearly empty tank.
Run the engine for 5-10 minutes to circulate the treated fuel throughout the entire carburetor system.
Then you can proceed to store the mower. This keeps the seals moist and the internals protected.

Common Mistakes To Avoid

A few simple errors can undermine your efforts. Being aware of these common pitfalls will ensure your mower is properly winterized.

Storing With Old Gasoline

This is the number one mistake. Old gas degrades, leaving sticky deposits. Always remove gas that’s more than 30 days old or treat it with stabilizer before storage. Never assume it will be fine; it rarely is.

Improper Fuel Disposal

Never pour gasoline on the ground, down a drain, or into regular trash. It’s a hazardous material that contaminates soil and water. Take it to a local hazardous waste recycling center or an auto parts store that accepts it. Some communities have specific collection days.

Neglecting Other Maintenance Steps

Removing the fuel is just one part of seasonal care. Don’t forget to also change the oil, clean or replace the air filter, and sharpen the blade. A comprehensive approach keeps your mower in top condition for years.

Frequently Asked Questions

How Do You Get Gas Out Of A Lawn Mower Without A Siphon?

If you don’t have a siphon, you can drain the gas by disconnecting the fuel line at the carburetor. Place a container underneath, loosen the clamp, and pull the hose off. You can also use the “run dry” method, though it’s less thorough. For mowers with a drain plug, that’s the easiest no-siphon option.

Is It Better To Drain Gas Or Use Stabilizer?

For long-term storage (over 3 months), draining the tank and carburetor is generally the best practice. It eliminates the risk entirely. Using a high-quality stabilizer in fresh gas is a good alternative for shorter periods or if you drain most of the fuel but leave a treated amount in the system to keep seals from drying out.

Can Old Gasoline Ruin A Lawn Mower Engine?

Yes, absolutely. Old gasoline loses its combustibility and forms a thick varnish and gum. This clogs the tiny jets and passages in the carburetor, preventing the engine from getting the right fuel-air mixture. This leads to hard starting, poor performance, and can eventually require a carburetor rebuild or replacement.

How Long Can Gas Sit In A Lawn Mower Before It Goes Bad?

Standard ethanol-blended gasoline can begin to degrade in as little as 30 days. Within 60-90 days, it often causes noticeable problems. Using fuel without ethanol (ethanol-free) or adding a stabilizer when you first fill the can extends this life to 6 months or more. Always try to use fresh fuel within a month for best results.

What Is The Fastest Way To Drain A Lawn Mower Gas Tank?

The fastest method is usually siphoning with a manual pump. It requires no tools or disassembly and can empty a tank in minutes. If your mower has a convenient drain plug, that is equally fast. Running the engine dry is quick but doesn’t remove fuel from the tank itself, only what the engine consumes.