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Your Kubota Lawn Mower is Leaking Fuel (Solved!)

You may be lucky enough to find a wet spot under your mower from a fuel leak. Many times, the only sign of a fuel leak on your mower is the gas odor that fills the air. Gas will evaporate leaving no physical sign of a fuel leak. This can make finding a leak on your Kubota increasingly difficult.

A Kubota lawn mower may be leaking fuel from the carburetor due to a bad gasket, stuck float or stuck float needle. It may also begin leaking fuel from other fuel components including the filter, fuel lines, tank, pump, and fuel shut-off valve.

I have put together a list of items to check on your Kubota mower when looking for the cause of a fuel leak.

Kubota lawn mower is leaking fuel

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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.

Items on Your Kubota Lawn Mower that Can Begin Leaking Gas

Kubota Carburetor is Leaking Gas

The carburetor regulates the amount of air and gas that is allowed into the cylinder to form a combustion. The carburetor stores a small amount of fuel in the bowl. The fuel that runs through your carburetor can cause gummy and crusty deposits to form affecting the carburetor.

These are the main items prone to leaking on your carburetor:

Gasket on your Kubota mower’s carburetor bowl

There is a gasket located between the carburetor bowl and the carburetor. The bowl is the part on the bottom of your carburetor held on with a screw. The gasket looks like a rubber band and forms a seal between the bowl and the carburetor.

The gasket becomes dry and brittle over time due to its location. It sits near the engine so it heats up when the engine runs and cools down when it is not. The stress caused by the changes in temperature can make the gasket dry. It loses its ability to seal properly causing the fuel collecting in the bowl to leak out of the gasket area.

If you find your gasket is leaking, replace your gasket. First, stop the fuel flow to your carburetor. Wipe down the outside of your carburetor to remove any dirt and debris and eliminated contaminates from entering the carburetor.

Next, Remove the screw under your carburetor bowl and remove the carburetor bowl. Have a rag ready to collect any gas in your bowl. Remove the old gasket and replace with a new gasket. Make sure you don’t get any carburetor cleaner or other substance on your gasket or you will have to purchase a new one.

Reinstall the carburetor bowl and tighten the screw to hold it to the carburetor. Start your fuel flow and check for leaking around the bowl. If you find additional leaks on your carburetor continue checking the float and float needle.

Stuck float in your Kubota mower’s carburetor

Look for a leak near the air intake port. A leak in this area may indicate you have a problem with your carburetor float. The float regulates how much gas is allowed to enter the carburetor bowl. When the float gets stuck and it is no longer able to regulate the amount of fuel in the bowl, fuel can continue to flow. This will cause the fuel to overflow and run out of your carburetor.

If the float in your Kubota carburetor is stuck, you will need to disassemble the carburetor to find the cause of the failure. You may be able to clean it or you may have to rebuild it. Read procedures on cleaning the carburetor in this article.

Stuck float needle in you Kubota mower’s carburetor

The float needle works with the carburetor float to keep gas flowing into the bowl. The needle can get stuck causing fuel to continue to flow and run out of the carburetor. You can tap the carburetor lightly with a rubber mallet or the handle end of a hammer to get it temporarily unstuck. This will only work temporarily. You will eventually have to replace the needle to repair it correctly.

Cracked or Soft Kubota Fuel Filter is Leaking Gas

The ethanol content in gasoline used in your Kubota can degrade plastics. This can make the plastic soft and begin leaking at the seams. Replace a leaking fuel filter. Be careful when removing the filter from the fuel line. The soft plastic can break off in the fuel line.

Install a new fuel filter with the arrow shown on the filter pointed in the direction of the Kubota’s fuel flow. The arrow should be pointed away from your fuel tank and toward your carburetor.

Kubota Fuel Pump is Leaking Gas

Just as fuel can degrade the fuel filter, it can do the same to your fuel pump. The pump can form leaks at the seams. The fuel pump is the component that pumps fuel from the fuel tank to your carburetor.

Your fuel pump should be located close to your carburetor and mounted on your engine. You will find a fuel line running from the fuel tank to the fuel pump and from the fuel pump to the carburetor. When the pump leaks, it is no longer able to build the pressure it needs to pump fuel. The pump must be replaced.

Seams on Your Kubota Fuel Tank Leak Gas

Fuel tanks on Kubota lawn mowers are made with a high-density polyethylene material. The seams on the fuel tank can fail causing the mower to leak. It is best to replace your fuel tank when you find a leak.

Kubota Fuel Shut-Off Valve is Leaking Gas

You may have a metal or plastic fuel shut-off valve on your Kubota lawn mower. The fuel shut-off valve can be found on the bottom of your fuel tank. It is used to start and stop fuel flow. Each type of valve, metal or plastic, is prone to leaking. Replace a leaking fuel shut-off valve.

Old Kubota Fuel Lines are Leaking Gas

Over time, your fuel lines can become dry, cracked and begin leaking. Check the ends of your fuel lines where they are secured with clamps. The clamps can puncture holes in the lines causing them to leak.

If your mower uses a pinch-style clamp, it is a good idea to replace them with a worm gear clamp because they are less likely to cause leaking. Replace any old fuel lines with new lines.

Bad Seal in Kubota Gas Cap Causing Gas to Leak

If you have check all the items above and still can’t find the cause of your leak, you should check your gas cap. If you can smell gas fumes, but don’t find a wet spot on your mower, there’s a chance the fuel is leaking around your gas cap. The fuel evaporates and only leaves the strong odor of fuel in the air.

The seal in the cap can fail and not form a seal when placed on your gas tank. To find a faulty seal, rock your Kubota back and forth splashing fuel from the tank up to the gas cap area. Watch to see if a wet spot forms around the fuel cap on the outside of your tank. Replace your gas cap when you find a leak.