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Your Honda Lawn Mower is Leaking Gas (Solved!)

There’s a strong odor filling your garage. You narrowed down the fuel leak to your Honda lawn mower, but you’re having trouble pinpointing the area of the leak. A fuel leak needs to be fixed before you continue to use your mower. No only because your Honda will go through excessive amounts of fuel, but also because fuel dripping onto your lawn can kill it.

A Honda lawn mower can begin leaking gas from using old fuel that can degrade and gum up your fuel components. The mower may leak from the fuel tank, shut-off valve, fuel filter, fuel lines, carburetor or gas cap.

I’ll share with you the main items to inspect while looking for a fuel leak on your Honda mower. Make sure to take safety precautions whenever you work on our Honda mower.

Honda lawn mower leaking gas

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

6 Places Your Honda Lawn Mower Can Start Leaking Gas

Begin looking for a leak at your fuel tank. Then follow the fuel line out of the tank checking all the fuel components attached to the fuel line.

Honda Mower Fuel Tank

Depending on your Honda lawn mower, you may have a metal or high-density polyethylene gas tank. Meal fuel tanks can begin to corrode and develop rust spots. These spots can develop holes allowing gas to leak out of the tank.

Replace the fuel tank if it is available. If your mower is older and the tank is no longer being manufactured, you will need to patch the hole using a material like JB Weld.

The seams on a polyethylene gas tank can eventually fail and begin to leak. Your best option for this style fuel tank is to replace it with a new tank.

Honda Mower Fuel Shut-Off Valve

Your Honda lawn mower may have a metal or plastic fuel shut-off valve. Both types of valves are prone to leaking. Check the valve and replace it if you find a leak from the valve.

Honda Mower Fuel Filter

If your Honda push mower uses a fuel filter, it can begin leaking at the seams. The fuel that sits in the filter can degrade and soften the plastic housing over time causing it to leak. Replace a leaking fuel filter making sure the replacement filter is installed with the arrow on the housing facing in the direction of the fuel flow. This means the arrow needs to be facing the carburetor and away from the fuel tank.

Honda Mower Fuel Lines

Rubber fuel lines will become dry with age and begin to crack. Fuel lines in this condition can develop leaks at the cracks. It can also begin leaking in the area where the line is attached to a component using a clamp. The clamp can puncture the line or become loose causing it to leak.

Use the fuel shut-off valve to shut off your fuel supply while you remove and replace the fuel line. If your Honda mower came with pinch style hose clamps, it’s a good idea to replace with a worm gear clamp because they are less likely to cause leaking.

Honda Mower Carburetor

Once the fuel leaves the tank, a little fuel is stored in the carburetor. Old fuel can form gummy and crusty deposits making parts on the carburetor stick. When the components are not functioning properly, fuel can overflow and run out of the carburetor.

If you find your fuel leak is coming from the area by the air intake, it is most likely due to a stuck float of float needle. The float on the carburetor indicates when to start and stop fuel flow into the carburetor bowl. When the float or float needle become stuck, it no longer can regulate fuel flow causing excess fuel to overflow.

You will have to unassembled the carburetor and identify the cause of the stuck float if you find a leak in this area. You may be able to clean the carburetor and the components using the instructions in this article or you may have to replace the float or needle.

Some people suggest tapping on your carburetor when you find your float needle is stuck. While this may work a time or two, it is not a permanent fix. You will have to tear your carburetor apart and replace the needed.

A fuel leak can also develop from the area between the bowl at the bottom of your carburetor and the carburetor. There is a carburetor gasket between these two areas that can become dry and brittle because of its location.

The gasket looks like a rubber band. Because it is located next to the engine. The stress of being hot when the engine is running and cold when it is not can cause the gasket to fail and lose its sealing capability. A carburetor gasket is an easy part to replace on your carburetor.

Replace a Honda mower carburetor gasket

  • Wipe down your carburetor so you don’t get dirt in it when you remove the bowl.
  • Remove the screw at the bottom of the carburetor and remove the bowl.
  • Remove the old gasket and install the new gasket. Be careful not to get any material, like carburetor cleaner, on the gasket or you’ll have to replace it.
  • Reinstall the bowl and screw. Tighten the screw to seal the bowl to the carburetor.

Honda Mower Gas Cap

There is a seal in your gas cap. When it fails to seal, fuel can leak out of the cap while you are running your mower and fuel is sloshing around the fuel tank and up to the cap. A wet spot will form around the outside of the cap area on the fuel tank. You may have not notice a fuel spot leak in this area because fuel evaporates into the air leaving no signs of leakage.

If you smell fuel in your mower storage area, but can’t find the cause of your fuel leak after checking all the items above, you need to check the fuel cap. To identify a bad seal in the cap, rock the mower back and forth to splash fuel up to the cap area and watch for a wet spot to develop around the cap. Replace the cap with a new Honda mower cap if you notice a wet spot.

In Summary

Always run good fresh fuel through your fuel system to minimize damage to your fuel components. Adding a fuel stabilizer will prevent your fuel from breaking down while reducing moisture buildup. Read this article on the right gasoline to use in your Honda mower to learn more about choosing the correct gasoline and storing it properly.