Your John Deere Lawn Mower Is Leaking Gas (Solved!)

You may not even notice you have gas leaking from your lawn mower until fumes fill your storage area. There are strong smells of gas filling the air.

It can be hard to find the spot your gas is leaking from because there are often no signs of wet spots. This is because gas evaporates so, without a wet spot, it can be tough to narrow down a fuel leak.

A John Deere lawn mower can begin leaking gas due to a failed gasket or stuck parts in the carburetor. A fuel leak can develop in your fuel lines, fuel filter, fuel pump, and around your gas cap.

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

This is Where Your John Deere is Leaking Gas

Carburetor is Leaking Gas

When you find a leak on your John Deere, there is a good chance the leak is coming from the carburetor. Once the gas leaves the fuel tank, a small amount of gas is stored in the carburetor.

Gas that sits in your mower can leave deposits that can cause the small components of your carburetor, including the gasket around the bowl, float, and float needle, to become clogged and stuck causing it to leak.

Gasket failure in the carburetor bowl on your John Deere mower

There is a gasket that looks like a rubber band located between the bowl on the bottom of your carburetor and the carburetor. The location of the carburetor on your John Deere causes the gasket to become dry and brittle.

Because the carburetor is located next to the engine, it constantly gets hot while the engine runs and cool when the engine is off. This change in temperature causes the gasket to lose its sealing capabilities over time.

If you notice fuel is leaking around the bowl, you must replace the gasket. To get to the gasket, first clean around the outside of your carburetor to remove dirt.

Remove the screw at the bottom of the carburetor bowl. Have a rag ready to collect any gas remaining in the bowl and remove the bowl.

Take off the old gasket and replace it with the new gasket. Reinstall the bowl and tighten the screw to secure the bowl to the carburetor.

Stuck float in your John Deere mower carburetor

The leak from your carburetor may be coming from the area near your air intake port. If you notice a leak in this area, you must check for a stuck carburetor float. When the float operates correctly, it regulates the amount of fuel allowed into the carburetor bowl.

A stuck float on your John Deere mower is unable to control when fuel is to stop flowing into the bowl. This causes fuel to overflow and leak out of the carburetor. A leak caused by a stuck float must be fixed by disassembling the carburetor to find and repair the cause of the stuck float.

You may be able to clean your John Deere’s carburetor to “unstick” the float or you may have to rebuild or replace it. You can find steps to clean your carburetor here.

Stuck float needle in your John Deere mower carburetor

Once you get inside your carburetor to look at the float, you may find the float is fine and the float needle is stuck. The needle works with the float to keep gas flowing into the bowl.

When your needle is stuck, you must rebuild your carburetor. A carburetor rebuild kit can be purchased from your local John Deere dealership.

To temporarily loosen your stuck needle, tap the carburetor with a rubber mallet or the rubber end of a hammer. This may work once or twice. You will have to replace the float needle to correctly fix your John Deere carburetor.

Fuel Filter is Cracked or Deteriorating

The fuel leak on your John Deere can be coming from a cracked or degraded fuel filter. Old gas sitting in your fuel filter can degrade the plastic of the filter and cause it to become weak and soft and cause leaking at the seams. Learn more about the effects of old gasoline here.

Replace your fuel filter if it is found to be the cause of your leak. Be careful when your plastic is soft. The filter ends can break off in the hose.

Because your fuel filter is necessary to keep dirt from entering your fuel system and engine, it’s important to regularly replace your filter annually when completing your John Deere service maintenance.

Bad Fuel Pump

Just like a gas can degrade your fuel filter, the same is true of your fuel pump. Check the seams of your pump for leaks. Replace the fuel pump with a new one when it is leaking.

Fuel Tank Leak

John Deere fuel tanks today are made with a high-density polyethylene material that can fail and leak at the seams. When this happens, it is best to replace your fuel tank when it develops a leak at the seam or it has been damaged.

John Deere Mower Fuel Shut-Off Valve

You will find a fuel shut-off valve on the bottom of your gas tank. It is common for these valves to develop leaks over time. The valve must be replaced with a new fuel shut-off valve to stop the leaking.

Old Fuel Lines on Your John Deere Mower

It is normal for your fuel lines to become dry and start to crack as they age. Fuel line leaks can also be caused by the clamps used on your John Deere to secure the fuel lines. These clamps can puncture the fuel hose.

You must replace the fuel lines that are cracked. As prevention, replace any lines that are starting to get dry and develop cracks before they begin leaking. It is also a good idea to replace your fuel clamps if your John Deere uses a pinch-style clamp.

These types of clamps are more likely to pinch your fuel lines and cause leaking. I like using a worm gear clamp because they are less likely to pinch your lines.

Bad John Deere Mower Gas Cap

The gas cap on your John Deere mower is designed to seal to your gas tank. The seal in your cap can go bad and fail to seal. This can cause fuel to leak around your gas cap when fuel is sloshed around the tank while operating your John Deere.

You may not have noticed a leak in this area because gas evaporates and will not leave any sign of leaking. To check for a bad seal on your gas cap, rock your mower back and forth to splash fuel around the gas cap area.

Replace your John Deere gas cap with a new cap if you notice wet spots forming around the outside of the cap.