Lawn Mower Storage: Why Draining The Fuel Tank Is A Mistake

Wondering how you can ensure your lawn mower and outdoor power equipment will be ready to roll when the grass turns green?

If you’ve checked your manufacturer’s guide, you’ve probably seen a suggestion to perform some preventive maintenance prior to storage. This is always a good habit to get into. Some manufacturers will also recommend running your equipment dry before putting it away for the winter.

While draining the fuel tank may sound like a good idea, it could harm your engine.

Running a lawn mower dry will make it harder for it to fire right up when it comes time to take it out of storage. This is true of all your outdoor equipment and tools, from mowers and blowers to trimmers and chainsaws.

Lawn equipment relies on three basic elements to work. If you don’t have all three, your engine will not run:

1. Air
2. Spark
3. Fuel

Clean air will always be available if you take time to clean or replace your air filter. And a clean, properly-gapped spark plug usually takes care of the spark.

But fuel? If you don’t maintain components that help properly distribute gas at the right time and in the right amount, your equipment might not perform well. In fact, it may not run at all.

Draining the tank harms your lawn mowers carburetor

Draining the tank harms the “heart” of your equipment. Think of one of the most important organs in your body: your heart. The lawn mower carburetor is, in many ways, your engine’s “heart.” It blends air and fuel and circulates these elements into an engine’s cylinders.

Each time you drain the gas tank, you inadvertently put stress on your equipment’s critical “organ.” Here’s what happens:

• Draining fuel allows oxygen to enter the lawn mower’s carburetor.
  It’s impossible to get every last drop of gasoline out. When oxygen attacks the small fuel droplets left behind, it causes gum and varnish. If this debris settles in the wrong place, such as a needle valve tip, the carburetor will need cleaning to work properly.
• Where there is air, there is water (damage).
  Allowing your gas tank to sit empty for long periods leaves a huge area for water vapor to condense. When moisture collects, it can trigger corrosion in the tank, fuel lines, carburetor and cylinders, and can even cause catastrophic engine failure if a big “gulp” is taken into the engine all at once. (If your mechanic says there is “white rust” in the carburetor, this is why.)
• Fuel system plastics and rubbers are designed to live in fuel.
  These parts can become brittle and crack when exposed to air.

What to do instead: Avoid risks with gas stabilizer.

Manufacturers sometimes recommend draining the tank to winterize a lawn mower because the worst thing you can do is leave old fuel in an engine during long periods of storage.

You may have followed this advice in the past without noticeable issues, but that doesn’t mean you’re in the clear. If draining the tank becomes a yearly habit, there’s a good chance you’re shortening the lifespan of your lawn mower and other tools.

There’s a much easier way to properly store your lawn equipment. To avoid damage, simply use a quality fuel stabilizer and fresh fuel before putting equipment away for the season.

Here’s how to winterize a lawn mower correctly

Step 1: Buy and stabilize fresh fuel for maximum protection.
Adding fuel stabilizer to old fuel will stop it from degrading further, but the fuel may already have broken down.

Step 2: Fill your tank 95% full with fresh, stabilized fuel.
Leaving a little room prevents the fuel from expanding and spilling in warmer weather, and reduces the risk of water vapor that can condense and contaminate fuel.

Step 3: Run the engine for a couple of minutes.
This gets the stabilized fuel into the carburetor and fuel lines.

That’s it!

While you should still consult with your manufacturer for product-specific equipment and engine maintenance tips, these simple steps apply to all engines, big and small. A few minutes on each piece of yard equipment can save hours when the grass starts growing and the season kicks off in spring.