How To Drain Gas From Briggs And Stratton Lawn Mower

Every seasoned gardener and lawn care enthusiast knows that a well-maintained lawn mower is the cornerstone of a pristine yard. Neglecting your equipment, especially when it comes to fuel, can lead to frustrating engine problems and costly repairs down the line.

Whether you’re preparing your trusty machine for winter storage, performing routine maintenance, or simply dealing with old, stale fuel, knowing how to drain gas from your Briggs & Stratton lawn mower is an invaluable skill.

This comprehensive guide will walk you through the safest and most effective methods, ensuring your mower runs smoothly season after season. We’ll cover everything from vital safety precautions to proper fuel disposal, equipping you with the expertise of a professional landscaper.

Why Draining Your Lawn Mower’s Gas Is Crucial

Many homeowners overlook the importance of proper fuel management. Yet, it’s one of the simplest ways to extend the life and efficiency of your Briggs & Stratton engine.

Over time, gasoline can degrade, especially with the ethanol content found in most modern fuels. This degradation can lead to significant problems for your mower.

Preventing Stale Fuel Damage

Gasoline, particularly ethanol-blended fuel, begins to break down after about 30 days. It can separate, leaving behind gummy residues and corrosive elements.

This stale fuel can clog your carburetor, foul spark plugs, and even corrode internal engine components. It’s a leading cause of hard starting or no-start issues after long storage periods.

Preparing for Winter Storage

Winterizing your lawn mower is essential in colder climates. Leaving fuel in the tank for months can lead to severe damage that becomes apparent only when you try to start it in spring.

Draining the fuel, or at least stabilizing it, is a critical step in ensuring a smooth start-up when the grass begins to grow again.

Routine Maintenance and Repairs

Sometimes, you need to drain the fuel to perform other maintenance tasks. This could include cleaning or replacing the fuel filter, servicing the carburetor, or tipping the mower for blade sharpening.

Having an empty fuel tank makes these tasks safer and less messy. It also prevents accidental fuel spills during adjustments.

Safety First: Essential Precautions Before You Begin

Working with gasoline requires extreme caution. Fuel is highly flammable, and fumes can be dangerous. Always prioritize safety to prevent accidents.

These steps are non-negotiable for your protection and the safety of your property.

Ensure Proper Ventilation

Always work in a well-ventilated area, preferably outdoors. If you must work indoors, ensure garage doors and windows are open to allow fumes to dissipate.

Never work in an enclosed space where gasoline fumes can accumulate, as this poses a significant fire and health hazard.

Allow Engine to Cool Completely

Hot engine components can ignite gasoline. Before you begin any fuel-draining procedure, turn off your lawn mower and allow it to cool down for at least 30 minutes to an hour.

A cool engine is a safe engine for fuel-related tasks.

Eliminate Ignition Sources

Remove all potential ignition sources from the work area. This includes open flames, pilot lights, heaters, electric tools that can spark, and even smoking materials.

Keep a fire extinguisher specifically rated for fuel fires (Class B) nearby as an added precaution.

Wear Personal Protective Equipment (PPE)

Protect yourself from fuel exposure. Wear safety glasses or goggles to shield your eyes from splashes.

Heavy-duty, fuel-resistant gloves are also crucial to prevent skin irritation and absorption. Long sleeves and pants can offer additional protection.

Use Approved Containers

Only use approved, fuel-resistant containers for collecting and storing gasoline. These are typically red plastic cans designed for fuel, with proper caps.

Never use open containers, glass jars, or containers not rated for fuel storage, as they can leak, break, or contribute to fire hazards.

Tools and Materials You’ll Need

Having the right tools at hand makes the job smoother and safer. Gather these items before you start the process.

• Fuel-resistant container (e.g., a gas can)
• Siphon pump (manual or electric) OR a section of clear tubing
• Wrenches or pliers (for fuel line clamps)
• Funnel
• Clean rags or absorbent towels
• Safety glasses
• Fuel-resistant gloves
• Small bowl or container (for carburetor draining)

How to Drain Gas From Briggs and Stratton Lawn Mower: The Fuel Line Disconnect Method

This method is often considered the most thorough way to remove fuel, as it drains both the tank and the carburetor bowl. It’s particularly effective if you suspect water or sediment in your fuel system.

It requires a bit more mechanical familiarity but is straightforward once you understand the components.

Locating the Fuel Line and Carburetor

First, identify the fuel tank, the fuel line running from the tank, and the carburetor. On most Briggs & Stratton engines, the fuel line is a rubber hose connecting the bottom of the fuel tank to the carburetor.

The carburetor is usually a metallic component positioned between the air filter and the engine block.

1. Position the Mower Safely: Place your mower on a flat, stable surface. Ensure the engine is cool and all safety precautions are in place.
2. Locate the Fuel Shut-Off Valve (If Applicable): Some Briggs & Stratton mowers have a small shut-off valve on the fuel line. If yours does, turn it to the “off” position. This minimizes initial fuel flow when you disconnect the line.
3. Prepare Your Collection Container: Position your approved fuel container and funnel directly beneath the carburetor or the lowest point of the fuel line.
4. Loosen the Fuel Line Clamp: Using pliers or a screwdriver (depending on the clamp type), slide the fuel line clamp away from the carburetor. You might need to gently twist the fuel line to loosen it from the carburetor’s inlet.
5. Disconnect the Fuel Line: Carefully pull the fuel line off the carburetor. Be prepared for fuel to start flowing immediately, especially if you don’t have a shut-off valve or forgot to close it. Direct the fuel line into your collection container.
6. Drain the Fuel Tank: Allow all the fuel from the tank to drain completely through the disconnected line. You may need to tilt the mower slightly to get the last drops out, but be careful not to spill oil or other fluids.
7. Drain the Carburetor Bowl: After the tank is empty, there will still be a small amount of fuel in the carburetor bowl. Look for a small screw on the bottom of the carburetor bowl. Place a small container beneath it and carefully loosen this screw to drain the remaining fuel. Tighten it once empty.
8. Reconnect the Fuel Line: Once all fuel has drained, reattach the fuel line securely to the carburetor. Slide the clamp back into its original position to hold the line firmly in place. Ensure a tight seal to prevent leaks.

Siphoning Gas From the Fuel Tank

Siphoning is a less invasive method for removing fuel, especially useful if you want to reuse the fuel or avoid disconnecting engine components. It’s generally quicker than the fuel line method if you have the right equipment.

This approach primarily drains the tank, leaving a small amount in the fuel lines and carburetor.

Using a Siphon Pump

A dedicated siphon pump is the cleanest and safest way to siphon fuel. These pumps come in various forms, from simple hand-squeezed bulbs to battery-operated models.

Always ensure your siphon pump is rated for gasoline.

1. Position the Mower: Place your mower on a level surface. Ensure the engine is cool and all safety precautions are strictly followed.
2. Open the Fuel Tank Cap: Remove the cap from the Briggs & Stratton lawn mower’s fuel tank to allow for air circulation and easier siphoning.
3. Insert Siphon Tube: Insert one end of your siphon pump’s intake tube into the fuel tank, ensuring it reaches the bottom of the tank.
4. Position Collection Container: Place your approved fuel container on the ground, lower than the fuel tank. Gravity assists the siphoning process.
5. Initiate Siphon:
   • Manual Siphon: Squeeze the bulb repeatedly to create suction until fuel starts flowing into your collection container.
   • Battery-Operated Siphon: Turn on the pump according to the manufacturer’s instructions.
   • Gravity Siphon (without pump): If using just a tube, submerge the tube fully in the fuel, then quickly place your thumb over one end. Pull the thumb-covered end out of the tank, keeping it lower than the fuel level, and quickly release your thumb into the collection container. Be careful not to ingest fuel.
6. Drain the Tank: Allow the fuel to flow until the tank is empty. You may need to adjust the tube’s position to collect the last bits of fuel.
7. Remove Siphon: Once drained, remove the siphon tube and securely replace the fuel tank cap. Wipe up any spills immediately with absorbent rags.

Running the Engine Dry

This method is simple but has some caveats. It involves letting the mower run until it consumes all the fuel in its tank, lines, and carburetor. While convenient, it’s not always the best option for long-term storage.

Running the engine dry helps clear the entire fuel system, but it doesn’t remove large quantities of old, contaminated fuel.

When to Use This Method

Running the engine dry is suitable if you have only a small amount of fuel left in the tank, and you plan to store the mower for a shorter period (a few weeks to a month).

It’s also an option if you’re using fresh, stabilized fuel and just want to ensure the system is completely clear before a very long storage.

1. Add Fuel Stabilizer (Optional but Recommended): If you plan to run the engine dry for storage, add a fuel stabilizer to the remaining fuel in the tank. Run the engine for 5-10 minutes to circulate the stabilizer through the fuel system.
2. Start the Mower: Begin by starting your Briggs & Stratton lawn mower as you normally would.
3. Let it Run: Allow the mower to run until it completely runs out of fuel and stalls. This ensures that all the fuel in the tank, lines, and carburetor has been consumed.
4. Attempt Restart: After it stalls, try to start it one or two more times. This helps to burn off any last residual fuel vapors in the carburetor.

Important Note: While this method empties the system, it still leaves behind any gum or varnish from stale fuel in the carburetor. For true long-term storage or if dealing with old, untreated fuel, draining via the fuel line or siphoning is superior.

Proper Disposal of Old Fuel

Never pour old gasoline down drains, onto the ground, or into regular trash. Gasoline is a hazardous waste and must be disposed of responsibly to protect the environment and public health.

Improper disposal can contaminate soil and water, and is often illegal.

Local Recycling Centers and Hazardous Waste Facilities

The best way to dispose of old fuel is to take it to a local hazardous waste collection facility or a recycling center that accepts fuels.

Many communities offer regular collection events for household hazardous waste. Check your local municipal waste management website for specific guidelines and locations.

Gas Stations and Auto Repair Shops

Some gas stations or auto repair shops may accept small quantities of old gasoline for recycling. It’s always best to call ahead and confirm their policy before bringing your fuel.

Ensure the fuel is in an approved, sealed container when transporting it.

Post-Drainage Maintenance Tips

Once you’ve successfully completed the process to how to drain gas from your Briggs & Stratton lawn mower, consider these additional steps to keep your machine in top condition.

These preventative measures will save you headaches and expense in the future.

Add Fuel Stabilizer to New Fuel

When refilling your tank for the next season, consider using fresh gasoline treated with a fuel stabilizer. This can prevent fuel degradation for up to two years.

It’s an excellent habit for any small engine, especially if your mower sits unused for extended periods.

Check and Clean the Air Filter

While you’re performing fuel maintenance, take a moment to inspect your air filter. A clogged air filter restricts airflow, leading to reduced engine performance and efficiency.

Clean or replace it as needed, following your mower’s manual.

Inspect the Spark Plug

Remove and inspect the spark plug. Look for signs of fouling, wear, or corrosion. A dirty or worn spark plug can cause misfires and poor starting.

Clean it with a wire brush or replace it if necessary. Ensure the gap is correctly set.

Change the Oil (Seasonal)

For seasonal storage, changing the oil is highly recommended. Old oil can contain contaminants that can damage engine components over time.

Refer to your Briggs & Stratton manual for the correct oil type and change intervals.

Troubleshooting Common Issues

Even with careful planning, sometimes things don’t go exactly as expected. Here are a few common issues and how to address them.

Knowing these solutions can prevent frustration and keep your project on track.

Fuel Won’t Drain

If fuel isn’t flowing, check for blockages. The fuel filter might be clogged, or the fuel line could be kinked.

Ensure the siphon tube reaches the bottom of the tank and isn’t blocked by debris.

Fuel Spills

Despite your best efforts, spills can happen. Immediately soak up any spilled fuel with absorbent rags or cat litter.

Dispose of contaminated materials properly with your other hazardous waste. Ensure the area is well-ventilated to dissipate fumes.

Mower Won’t Start After Draining and Refilling

If your mower won’t start after you’ve drained and refilled it with fresh fuel, check a few things:

• Fuel Shut-Off Valve: Ensure it’s in the “on” position.
• Fuel Line Reconnected: Double-check that all fuel lines are securely reattached and clamps are tight.
• Primer Bulb: Prime the carburetor a few extra times to ensure fuel is drawn into the system.
• Spark Plug: The spark plug might be wet from residual fuel or need cleaning/replacement.

FAQ: Your Questions Answered

Q1: Can I Just Leave the Gas in My Mower Over Winter If I Add a Fuel Stabilizer?

A1: While adding a fuel stabilizer is far better than doing nothing, completely draining the fuel is the most ideal option for long-term winter storage. Stabilizer slows degradation, but draining ensures no stale fuel issues whatsoever. If you do stabilize, run the engine for 5-10 minutes to circulate the treated fuel through the entire system before storage.

Q2: How Often Should I Drain the Gas From My Briggs & Stratton Lawn Mower?

A2: It’s best practice to drain the fuel if you anticipate storing the mower for more than 30-60 days, especially for winter. For regular use, if you consistently use up the fuel within a month, you likely won’t need to drain it unless you’re performing maintenance or notice performance issues from stale fuel.

Q3: What Type of Fuel Container Should I Use to Collect the Drained Gas?

A3: Always use an approved, red plastic fuel can with a tight-fitting cap, specifically designed for gasoline storage. These containers are made from fuel-resistant materials and have safety features to minimize spills and evaporation. Never use open buckets, glass bottles, or non-approved plastic containers.

Q4: What If My Briggs & Stratton Engine Doesn’t Have a Fuel Shut-Off Valve?

A4: Many smaller Briggs & Stratton engines on walk-behind mowers do not have a fuel shut-off valve. In this case, when you disconnect the fuel line, fuel will flow immediately. Be prepared with your collection container positioned and ready before disconnecting the line. Work quickly and carefully.

Q5: Can I Reuse the Drained Gasoline in My Car?

A5: It depends on the age and condition of the drained gasoline. If the fuel is relatively fresh (less than 30 days old) and you drained it for maintenance, you might be able to mix it with a full tank of fresh gas in your car. However, if the fuel is old, discolored, or smells sour, it’s best to dispose of it properly rather than risk damaging your car’s engine.

Conclusion: Empowering Your Lawn Care Journey

Mastering how to drain gas from your Briggs & Stratton lawn mower is a fundamental skill that every homeowner and DIY gardener should possess. It’s a simple yet incredibly effective way to prevent costly engine damage, ensure reliable starts, and extend the lifespan of your valuable equipment.

By following the detailed steps and safety precautions outlined in this guide, you’re not just performing maintenance; you’re investing in the longevity and performance of your lawn mower.

Embrace these practices, and you’ll enjoy a healthier, more beautiful lawn with less hassle, season after glorious season. Happy mowing!

Taylor Galla Founder of Garden Aider

• Mechanical engineer
• Gardening since 2010
• Univ. of Nevada, Reno

From the author's notebook

Taylor pairs an engineer's eye with years of hands-on work in soil, lawns and outdoor machinery. He tests ideas in his own garden, keeps tractors and mowers running himself, and speaks to local horticulture groups. Every Garden Aider guide is written to be practical, accurate and safe to follow.

“To bring life alive, you just need to mix some love with the compost, bedding, and gardening machines.”

Published Jul 6, 2026