How to Drain Gas from a Lawn Mower (Easy Steps + Model-Wise Guide)

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If your lawn mower has old fuel, it can cause hard starts, sputtering, or even engine damage. Gasoline degrades over time—especially ethanol-blended types—and can leave sticky deposits that clog the carburetor and fuel lines.

Learning how to drain gas safely and properly not only keeps your mower running efficiently but also extends its lifespan.

Whether you own a Honda, Toro, Craftsman, John Deere, Husqvarna, Cub Cadet, or Briggs & Stratton-powered mower, the process is nearly the same.
This guide will show you:

• Step-by-step instructions to drain gas safely
• Multiple methods (with and without siphon)
• Model-wise notes
• Storage and safety tips

🧠 Why You Should Drain Gas from a Lawn Mower

Draining old fuel is essential when:

• You’re storing the mower for winter
• You’ve accidentally filled it with bad or wrong fuel
• The mower won’t start or is sputtering due to old gas
• You’re replacing the carburetor or fuel line

Gasoline older than 30 days starts to oxidize and break down, forming gum and varnish that clogs the carburetor jets.
Ethanol fuels (E10) absorb moisture from the air, leading to corrosion and phase separation (water and gas layers).

🔧 Tip: If you’re not draining the tank, use a fuel stabilizer like STA-BIL or Sea Foam to keep gas fresh up to 2 years.

⚙️ Tools You’ll Need

• Fuel siphon pump or turkey baster
• Fuel-safe container (gas can)
• Pliers or hose clamp
• Screwdriver (flathead or Phillips)
• Paper towels or rags
• Gloves and safety glasses
• Optional: Fuel line removal tool, funnel

🔥 Safety First

1. Work outdoors or in a well-ventilated area.
2. Keep open flames, sparks, and cigarettes away.
3. Wear gloves and safety glasses to avoid skin or eye contact.
4. Ensure the engine is cool before starting.

⚠️ Gas vapors are flammable—never drain indoors or near a water heater.

🧰 How to Drain Gas from a Lawn Mower — 3 Methods

Method 1: Using a Fuel Siphon Pump (Safest & Cleanest)

This is the easiest and safest method for most mowers, especially push mowers.

🔹 Step 1: Prepare the Mower

• Move the mower to level ground.
• Remove the gas cap to relieve pressure.
• Disconnect the spark plug wire for safety.

🔹 Step 2: Insert the Siphon Hose

• Insert one end of the siphon tube into the fuel tank.
• Place the other end into a fuel-safe container.

🔹 Step 3: Start Siphoning

• Squeeze the pump bulb until fuel begins flowing.
• Let gravity complete the siphon action.

🔹 Step 4: Drain Remaining Fuel

• When flow stops, gently tilt the mower toward the fuel cap to drain residual fuel.

🔹 Step 5: Wipe Clean

• Remove hose, wipe spills, and close the gas cap securely.

🧠 Pro Tip: After draining, run the mower until it stalls to clear any leftover gas in the carburetor.

Method 2: Draining Through the Fuel Line

For mowers with a removable fuel line, this method ensures a complete drain.

🔹 Step 1: Locate the Fuel Line

• The fuel line connects the tank to the carburetor.
• Clamp the line using pliers to stop flow.

🔹 Step 2: Remove the Fuel Line

• Place a container under the carburetor.
• Use pliers to slide off the spring clamp and detach the line.
• Let fuel drain completely into the container.

🔹 Step 3: Reattach the Line

• Once drained, reconnect and secure the clamp.
• Inspect the line for cracks — replace if brittle.

⚠️ Be cautious — this method can be messy. Always have rags handy.

Method 3: Draining Through the Carburetor Bowl

If your mower has a drain plug or bolt at the bottom of the carburetor, use this method for a thorough clean-out.

🔹 Step 1: Locate the Carburetor Bowl

• Usually found below the air filter and fuel line.

🔹 Step 2: Place a Container Beneath

• Position a small bowl or can to catch draining gas.

🔹 Step 3: Loosen the Drain Bolt

• Using a wrench, carefully loosen the small bolt at the bowl’s base.
• Allow gas to flow completely out.

🔹 Step 4: Tighten the Bolt

• Once drained, re-tighten to avoid leaks.

💡 This method is best for Honda, Toro, and Briggs & Stratton mowers with drain bolts.

🚫 How to Drain Gas Without a Siphon or Fuel Line Removal

If you don’t have tools, you can still remove most gas easily.

1. Use a turkey baster or large syringe to draw fuel out of the tank.
2. Tilt the mower carefully to pour fuel into a container (through spout).
3. Use a clean cloth or sponge to soak up remaining fuel residue.

⚠️ Never flip the mower with oil or gas inside — always drain oil first if tilting significantly.

🧩 Model-Wise Lawn Mower Gas Draining Guide

🧠 Pro Tip: For riding mowers, always disconnect the battery before draining to avoid spark ignition.

🧪 Signs You Need to Drain Old Gas

• Mower won’t start after sitting for months
• Starts but dies after a few seconds
• Sputtering or misfiring while mowing
• Strong sour or varnish-like smell from the tank
• Visible separation in fuel (clear layer = water)

If you notice any of these, drain the fuel completely and replace it with fresh, ethanol-free gasoline.

🔋 After Draining — What To Do Next

1. Clean the Carburetor Bowl

Spray carb cleaner to remove residue. Old gas leaves gum that clogs jets.

2. Replace the Fuel Filter

Dirty filters trap debris and reduce flow. Replace every season for best results.

3. Add Fresh Gasoline

Refill with clean fuel — preferably non-ethanol or stabilized.

4. Run the Mower

Start the mower to circulate fresh fuel through the system.

⚙️ Optional: Add Sea Foam or STA-BIL to your gas to prevent moisture buildup and keep the carb clean.

🧼 How to Store a Lawn Mower After Draining

If storing for winter or long periods:

1. Drain all fuel or add stabilizer to prevent varnish.
2. Run the engine until it stops — ensures carb is dry.
3. Check oil — change if dirty.
4. Remove spark plug and add a drop of oil to the cylinder.
5. Clean deck and underside to prevent rust.
6. Store in a dry, covered space.

💵 Service and Repair Costs

💡 If your mower has been sitting for over a year, consider cleaning the carburetor along with draining fuel.

⚠️ Common Mistakes to Avoid

❌ Draining gas near flames or inside garages
❌ Using plastic bottles for fuel storage (melts or leaks)
❌ Forgetting to reconnect fuel line or spark plug
❌ Tilting mower with oil inside (causes smoke and leaks)
❌ Disposing of gas improperly

✅ Always dispose of old gasoline at a local recycling center or hazardous waste facility.

🧠 FAQs

1. Can I leave gas in my mower over winter?

Not recommended. Drain it or add stabilizer — old fuel causes hard starts and carb damage.

2. Can I reuse drained gas?

Only if it’s less than 30 days old and free of debris. Otherwise, discard it safely.

3. How long does gasoline last in a mower?

Regular fuel: 30–60 days.
Stabilized fuel: up to 12–24 months.

4. Can I drain fuel by running the mower dry?

Yes — simply run until it stalls. It won’t remove every drop but helps prevent varnish.

5. What’s the best fuel for lawn mowers?

Use E0 or E10 gasoline (87–91 octane). Avoid E15 or E85 ethanol blends.

✅ Summary: Quick Reference

Result: Fresh fuel, smoother starts, and longer engine life.

📚 References

1. EPA Guidelines: Safe Disposal of Gasoline and Oil

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David Holtzman

I’m David man behind Lawn Mowerly; I’ve been dealing with lawnmowers and Tractors with my father since I was a kid. I know every make and model and what each one is capable of and love helping people find the perfect equipment for their needs.