If your lawn mower won’t start, old gas is often the culprit. Learning how to get old gas out of a lawn mower is the essential first step to getting your equipment running again. Stale gasoline can cause starting issues, making its removal a critical first step in troubleshooting. Gasoline degrades over time, forming gummy residues and varnish that clog the delicate fuel system. This guide provides clear, step-by-step methods to safely remove old fuel and get your mower back in action.
How To Get Old Gas Out Of A Lawn Mower
There are several effective methods for removing old gasoline, and the best one for you depends on your mower’s design and your comfort level. The primary goal is to drain the fuel tank and the carburetor completely. Before you start, always work in a well-ventilated area, away from sparks or open flames, and have the proper containers ready for the old fuel. You’ll need safety glasses, gloves, a siphon pump or turkey baster, a container for old gas, and fresh fuel stabilizer for your new gasoline.
Safety Precautions Before You Begin
Gasoline is highly flammable and its fumes are hazardous. Never skip these safety steps. Your work area is the first consideration. Perform this task outdoors or in a garage with the door wide open. Never work in a basement or enclosed space. Ensure you have a Class B fire extinguisher nearby, just in case. Always disconnect the spark plug wire to prevent any accidental engine starts during the process. This is a simple but critical step for safety.
Essential Safety Gear
- Safety glasses to protect your eyes from splashes.
- Chemical-resistant gloves (nitrile is a good choice).
- A stable, approved fuel container for the old gas.
- Absorbent materials like kitty litter or rags for spills.
Method One: Siphoning The Fuel Tank
This is the most common and straightforward method for removing gas from the tank. Most lawn mower tanks have a small opening, making a manual pump siphon the ideal tool. You can find these at any auto parts store. First, place your approved waste container on the ground, lower than the mower’s fuel tank. Insert the siphon’s tube all the way into the mower’s tank. Then, pump the bulb or use the primer mechanism until you see fuel flowing into your container. Let it drain until the tank is empty.
Steps For Effective Siphoning
- Position your mower on a flat, level surface.
- Insert the siphon tube deep into the fuel tank.
- Pump the siphon bulb until fuel begins to flow.
- Direct the outflow tube into your waste fuel container.
- Allow the tank to drain completely, tipping the mower slightly if needed to get the last bit.
Method Two: Using A Turkey Baster Or Hand Pump
For smaller tanks or if you don’t have a siphon, a simple turkey baster (dedicated to this purpose only) or a small hand pump works well. The process is similar but more manual. Insert the baster or pump tube into the tank, squeeze the bulb or work the pump to draw the fuel up, and then transfer it to your disposal container. This method requires a bit more patience but is very effective and inexpensive. Be careful not to spill any fuel during the transfer between containers.
Method Three: Draining Via The Fuel Line Or Carburetor
If siphoning isn’t possible or you need to clear the entire system, draining from the fuel line is the next step. This ensures old fuel is removed from the carburetor bowl as well. First, use a clamp or pinch-off tool to clamp the fuel line between the tank and the carburetor. Then, place a container under the carburetor. Carefully disconnect the fuel line from the carburetor inlet. Release the clamp and allow the fuel from the tank to drain into your container. Finally, to drain the carburetor bowl, locate the drain screw on the bottom of the bowl, loosen it, and let the residual fuel drain out.
Identifying Carburetor Components
- Fuel Line: The rubber or plastic hose connecting the tank to the carb.
- Carburetor Bowl: The small, cup-shaped metal chamber at the bottom of the carburetor.
- Drain Screw: A small screw, usually on the very bottom of the bowl.
What To Do With The Old Gasoline
Never pour old gasoline down a drain, onto the ground, or into the regular trash. It is a hazardous material and must be disposed of properly. The best option is to take it to a local hazardous waste disposal facility or a recycling center that accepts old fuel. Many auto parts stores and some service stations also offer used oil and fuel recycling. Store the old gas in a clearly labeled, sealed container until you can dispose of it. Mixing it with fresh gas is not recommended, as it will degrade the new fuel’s quality.
Cleaning The Fuel System After Draining
Simply removing the old gas isn’t always enough. If the fuel was very old, varnish and gum may remain. For a thorough cleaning, consider using a fuel system cleaner. After draining, add a small amount of fresh fuel mixed with a quality fuel system cleaner to the tank. Swirl it around and try to run the engine for a few minutes to circulate the cleaner through the carburetor jets. If the mower still won’t start, the carburetor may need a manual cleaning or rebuild, which is a more advanced task.
Preventing Old Gas Problems In The Future
The best solution is to avoid the problem altogether. Always use a fuel stabilizer in every gallon of gas you put in your lawn mower, especially if you won’t be using it for a month or more. Sta-bil is a popular brand. At the end of the mowing season, either run the engine until the tank is completely empty or fill the tank to the top with stabilized fuel to prevent condensation. This simple habbit can save you a lot of trouble next spring. Also, try to use fresh gasoline within 30 days of purchase for best results.
End-Of-Season Storage Tips
- Add fuel stabilizer to your gas can, not just the mower’s tank.
- Run the engine for 5 minutes to circulate the stabilized fuel.
- Either drain the tank and carburetor completely OR fill the tank to the brim.
- Store your mower in a cool, dry place.
When To Seek Professional Help
If you’ve drained the old gas, added fresh stabilized fuel, and your mower still refuses to start, the issue may be more serious. Persistent problems often indicate a clogged carburetor that needs a deep clean or a rebuild. Other issues could include a fouled spark plug, bad ignition coil, or a clogged air filter. If you’re not comfortable disassembling the carburetor, taking your mower to a small engine repair shop is a wise investment. They have the tools and expertise to properly clean and adjust the fuel system.
Frequently Asked Questions
How Long Does It Take For Gas To Go Bad In A Lawn Mower?
Gasoline can begin to degrade in as little as 30 days. Within 3-6 months, it can become stale enough to cause starting and performance problems. Ethanol-blended fuel attracts moisture and separates even faster, leading to phase separation which is particularly damaging.
Can You Mix Old Gas With New Gas?
It is not recommended. While diluting a small amount of old gas with a large amount of fresh gas might work in a pinch, the old fuel will contaminate the new gas and reduce its effectiveness. For optimal engine performance and longevity, always use fresh, stabilized fuel.
What Are The Signs Of Bad Gas In A Lawn Mower?
The most common signs are the engine failing to start, sputtering and dying during operation, loss of power, and a rough idle. You might also smell a sour, varnish-like odor from the gas tank, which is a clear indicator of degraded fuel.
Is It Necessary To Drain The Carburetor Bowl?
Yes, for a complete fuel system flush. The carburetor bowl holds a reserve of fuel, and if you only drain the tank, old gas remains in the bowl and can still cause problems. Draining the bowl ensures you remove all the old fuel from the system.
How Do You Start A Lawn Mower After Removing Old Gas?
After refilling with fresh, stabilized gasoline, prime the system if your mower has a primer bulb. Set the throttle to the choke position, and pull the starter cord. It may take a few extra pulls to draw the new fuel into the carburetor. Once it starts, let it run for a few minutes to ensure smooth operation.