Water in Your Lawn Mower Gas Tank? How I Saved a Toro Recycler Today

 Two weeks ago, during a seasonal landscape consultation in Naperville, Illinois, a client pointed toward his Craftsman tractor and a trusty Toro Recycler push mower sitting under a leaky tarp. "They both stalled right after the heavy storm last weekend," he told me.

It’s a story I hear every spring. Whether it’s a loose gas cap during a downpour or using an old plastic fuel can that’s been sweating inside a humid garage, water gets into lawn mower gas tanks more often than you think.

Because water is heavier than gasoline, it immediately sinks to the bottom of the tank and gets sucked straight into the fuel lines. If you try to crank the engine, it will sputter, pop, and die. If you’re dealing with this right now, don't panic. Here is exactly how I saved that Toro Recycler with a Briggs & Stratton engine today, and how you can do the same.

1. Step 1: The Visual Confirmation (Spotting the "Two-Layer" Liquid)

Before you start tearing things apart, you need to confirm what's inside. Disconnect the spark plug wire for safety, then disconnect the main fuel line leading to the carburetor. Drain a small amount of the fuel into a clear glass jar.

 The Master Detail: Look closely at the jar. If there is water, you will see a clear, distinct horizontal line separating two liquids. The gasoline floats on top, while the water sits at the bottom like a bubble. If you see this phase separation, you must drain the system completely.

2. Step 2: Draining the Tank and the E10 Ethanol Problem

Most gas stations down the street sell E10 fuel (10% ethanol). The problem with ethanol is that it acts like a magnet for moisture. Over the winter, or during a humid storm, the ethanol absorbs water from the air until it reaches a tipping point and separates from the gas.

 How to fix it: Clamp the fuel line, place a fuel-safe container underneath, and let the entire tank empty out. Do not try to save this gas; it’s ruined. If you have a Honda GCV160 or a similar modern overhead cam engine, ensuring a completely dry tank is critical because their tolerances are incredibly tight.

3. Step 3: Purging the Carburetor Bowl

Even if the tank looks bone dry, about two tablespoons of pure water are still trapped inside the carburetor bowl.

 How to do it: Grab a 1/2-inch wrench and carefully remove the small brass bolt at the very bottom of the carburetor cup (the bowl). Let the trapped water drain onto a clean rag. You’ll notice a gooey, milky residue if the water has been sitting there for a while. Wipe the bowl clean, check that the small rubber O-ring gasket is intact, and bolt it back together.

4. Step 4: The Sea Foam Treatment and Fresh Fuel

Now that the plumbing is clear, refill the tank with fresh, high-quality unleaded gasoline. If you can find it, always buy ethanol-free gas (often labeled as REC-90) for your small engines to prevent future phase separation.

 The Pro Move: Pour 2 ounces of Sea Foam Motor Treatment directly into the fresh gas. Sea Foam acts as a stabilizer and a solubilizer. It will safely bond with any microscopic water droplets remaining in the fuel system and allow them to pass through the engine without causing a sputter.

What to Expect Upon Starting (The White Smoke Phenomenon)

Once everything is reassembled, give the starter cord 3 to 4 firm pulls. The engine might hesitate, cough, or blow a brief cloud of thick white smoke out of the muffler for the first two minutes.

Don't worry—this is completely normal. That white smoke is just the engine safely burning off the last remnants of moisture and the Sea Foam cleaning out the cylinders. Once the smoke clears, your mower will roar back to life, running smoother than ever.