Knowing how to drain gas from your lawn mower is essential for storage, troubleshooting, or routine maintenance. This guide walks you through safe, easy methods using common tools—whether you’re dealing with stale fuel, water contamination, or just preparing your mower for winter. With clear steps and expert tips, you’ll keep your engine healthy and avoid costly repairs.
Knowing how to drain gas from your lawn mower is a vital skill every homeowner should master. Whether you’re storing your mower for winter, dealing with old fuel, or suspecting water contamination, safely removing gasoline prevents engine damage and keeps your equipment running smoothly. This comprehensive guide walks you through everything—from preparation to cleanup—using simple tools and techniques anyone can follow.
Why Draining Gas Matters
Gasoline breaks down over time, especially when stored with ethanol. After about 30 days, it starts to degrade, forming gum and varnish that clog fuel lines and carburetors. In cold weather, water in the tank can freeze and crack components. Draining your mower’s gas tank removes these risks, ensuring your engine starts reliably when you need it. Plus, it’s eco-friendly—proper disposal keeps harmful chemicals out of soil and waterways.
Before You Start: Safety First
Always work in a well-ventilated area, preferably outdoors. Gasoline fumes are flammable and can cause dizziness or nausea. Wear gloves to protect your skin from fuel absorption. Have a fire extinguisher nearby, and never smoke or use lighters during the process. Keep children and pets away from the work area.
Tools and Supplies You’ll Need
– A clean, dry container (at least 1 gallon capacity)
– A siphon pump or turkey baster
– A funnel
– Safety goggles and gloves
– A rag or paper towels
– A wrench or socket set (if removing the fuel cap or drain plug)
– A flashlight (to see inside the tank if needed)
Step 1: Prepare Your Work Area
Clear a flat, stable surface away from buildings, vehicles, and direct sunlight. Lay down old newspapers or a tarp to catch spills. Position your collection container where it won’t tip over. If you’re working in cold weather, warm the gas slightly by placing the mower in a garage—this helps it flow more easily.
Step 2: Run the Mower Until It Stops
Start your mower and let it run until it sputters and dies. This burns off any residual fuel in the carburetor, preventing it from gumming up later. If your mower won’t start, skip this step and move to the next one. Running it dry also reduces the amount of fuel left in the tank for draining.
Step 3: Locate the Fuel Tank
Most push mowers have a fuel cap on top of the engine housing. Riding mowers may have a separate gas tank near the engine or under the seat. Check your owner’s manual if you’re unsure. The tank will usually have a fuel line connected to it—this is where you’ll drain the gas.
Step 4: Remove the Fuel Cap
Unscrew the fuel cap slowly to release pressure. You might hear a hissing sound—that’s normal. Set the cap aside in a safe place. If the cap is stuck, gently tap it with a rubber mallet or use a soft cloth for grip.
Step 5: Drain the Gas Using a Siphon
Insert the siphon hose into the fuel tank, below the fuel level. Place the other end into your collection container. Squeeze the bulb on the siphon and let it draw fuel automatically. Most small mowers hold 1–2 gallons, so this step takes just a few minutes. If your mower doesn’t have a siphon port, you can use a turkey baster or manual pump.
Alternative: Manual Draining with a Funnel
If you don’t have a siphon, tilt the mower slightly (use a jack or sturdy block to support it). Insert a funnel into the fuel fill neck and carefully pour the gas into your container. Be cautious—gasoline is heavy and can splash. Work slowly to avoid spills.
Step 6: Check for Water or Sediment
Once the tank is mostly empty, look for cloudy liquid or sludge at the bottom. This indicates water contamination or old fuel residue. If present, drain a bit more to remove it. You can also shake the container gently—sediment will settle at the bottom.
Step 7: Clean the Fuel Tank (Optional)
For stubborn buildup, add a small amount of fresh gasoline and a fuel system cleaner. Let it sit for 10–15 minutes, then drain again. This helps dissolve varnish and gum. Never use water to clean the tank—it will mix with fuel and cause problems.
Step 8: Dispose or Store Used Gas Properly
Never pour gasoline down storm drains or onto the ground. Take it to a local hazardous waste facility or auto parts store that accepts used fuel. Some retailers offer free recycling. Label your container clearly: “Used Gasoline – Flammable.” Store it in a metal container away from heat sources.
Step 9: Refill with Fresh Fuel (If Needed)
After draining, you can refill your mower with fresh, ethanol-free gasoline. Use a funnel to avoid spills. Add a fuel stabilizer if storing the mower for more than 30 days—this prevents future degradation.
Pro Tip:
Always check your lawn mower manual for model-specific instructions. Some Briggs & Stratton or Honda mowers have drain plugs under the carburetor that make draining even easier. Refer to guides like How To Drain Oil From A Lawn Mower for related maintenance tips.
Troubleshooting Common Issues
Problem: Gas won’t flow out.
Solution: The fuel line might be kinked or clogged. Double-check connections and ensure the tank isn’t tilted too far. For older mowers, the float valve in the carburetor might be stuck—consider cleaning or replacing it.
Problem: Spills during draining.
Solution: Work slowly and keep a rag handy. If you spill, soak up the liquid immediately and dispose of it safely. Avoid using paper towels near open flames—they can ignite.
Problem: Mower won’t start after draining.
Solution: Old fuel residue might still be in the carburetor. Try adding fresh gas and a carburetor cleaner. If that doesn’t work, you may need to remove and clean the carburetor—see our guide on How To Clean Carburetor On Briggs And Stratton Lawn Mower.
When to Drain Gas: Common Scenarios
– **Winter storage:** Drain gas before cold months to prevent freezing.
– **Old fuel:** If gas is more than 30 days old, drain it even if the mower works fine.
– **Water contamination:** Cloudy or separated liquid means water is present—drain immediately.
– **Routine maintenance:** Every 2–3 months during mowing season helps keep the system clean.
– **Pre-sale prep:** If selling your mower, drain old gas and refill with fresh fuel for better resale value.
Environmental Responsibility
Used gasoline contains benzene and other toxins that harm wildlife and contaminate groundwater. Always recycle through approved channels. Many auto parts stores, like AutoZone or O’Reilly, accept up to 5 gallons for free. Never burn or bury used gas—it’s illegal in most areas.
Final Tips for Long-Term Mower Health
After draining, inspect the fuel lines for cracks or leaks. Replace them if brittle or cracked. Store your mower in a dry place with the tank half-full of fresh gas and a stabilizer. This prevents moisture buildup and keeps the engine ready to go.
Knowing how to drain gas from your lawn mower isn’t just about convenience—it’s about protecting your investment. With these steps, you’ll extend your mower’s life, avoid costly repairs, and keep your lawn care routine hassle-free. Whether you’re a seasoned DIYer or a first-time user, this process is simple, safe, and essential.
Key Takeaways
- Old or contaminated gas harms your mower’s engine—draining it prevents clogs and corrosion.
- Always drain gas outdoors—gasoline is flammable and should never be done near sparks or open flames.
- Use a siphon or manual pump for most small mowers—these tools make the job quick and clean.
- Label and recycle used fuel properly—never pour gasoline down drains or into the environment.
- Refill with fresh, ethanol-free gas—this extends engine life and improves performance.
- Check your mower’s manual first—some models have drain plugs or special procedures.
- Wipe up spills immediately—gasoline evaporates slowly and poses fire risks.