Gas dripping onto the lawn can leave a trail of dead grass providing evidence your lawn mower is leaking. You might not even see a physical sign of a leak, but you sure can smell gas in the air. Either way, you need to find the fuel leak and repair it.

A Ferris lawn mower may be leaking gas from the carburetor due to a bad carburetor bowl gasket, stuck float, or stuck float needle. It may also begin leaking from the fuel filter, fuel shut-off valve, fuel line, fuel pump, gas cap, or fuel tank seam.

Gas fumes are harmful. Always work in a well-ventilated area away from any combustible items. Protect your eyes using safety glasses. Follow all additional safety procedures prior to troubleshooting and repairing your Ferris zero turn or walk-behind.

Reasons a Ferris Lawn Mower May Be Leaking Gas

Carburetor is Leaking Gas on a Ferris Mower

A commonplace on a Ferris mower to develop an oil leak is the carburetor. This is the place where a little gas is stored once it leaves the fuel tank.

Old gas that sits in the carburetor can leave behind varnish and gummy deposits that can cause the small parts located inside the carburetor to stick and not function properly. When this happens, gas may run out of the carburetor. Another place you may find a leak is from a failing carburetor gasket.

Gasket failure in the carburetor bowl on a Ferris mower

Begin looking for a fuel leak by checking the carburetor for a leak coming from between the carburetor and the bowl located on the bottom of the carburetor. The bowl is where a little fuel is stored.

There is a small gasket that provides a seal between the carburetor and the bowl. It looks a lot like a rubber band. This gasket can become dry and brittle with age. This is mostly because of its proximity to the engine.

Being close to the engine, the gasket is subjected to swings in temperature that put stress on the gasket. The gasket gets hot when the engine is running and cools down when it is not.

Due to the extreme temperature changes, the gasket can become dry losing its ability to seal the bowl to the carburetor.

If you do find a leak between the carburetor and the bowl, you will have to replace the carburetor gasket. Obtain a replacement gasket for your model engine carburetor.

You will need to get the model and spec number from the engine. Note: This is different from the mower model and serial number.

Follow these steps to replace the carburetor gasket on a Ferris mower:

• Wipe around the outside of the carburetor to remove dirt and any debris stuck to it.
• Remove the screw located at the bottom of the carburetor bowl. Have a rag ready to collect any gas remaining in the bowl.
• Lower the bowl to remove it.
• Remove the old gasket and replace it with a new gasket.
• Don’t get any lubricants on the new gasket so you don’t damage it.
• Reinstall the bowl and secure it by tightening the screw.

Stuck float in a Ferris mower carburetor

If you didn’t find a leak coming from the gasket or you repaired the gasket leak and continue to have a leak coming from a different area of the carburetor, look near the top of the carburetor by the air intake port.

When gas is leaking from this area, the most likely issue is a stuck carburetor float. The float is the part that regulates the amount of fuel that is allowed into the bowl.

So, when it becomes stuck, the float may not be able to stop gas from flowing into the carburetor bowl. It can cause your Ferris mower’s carburetor to overflow and run out of the carburetor.

A leak that is caused by a stuck float must be repaired by disassembling the carburetor and repairing the stuck float. You may be able to clean your Ferris carburetor to free up the float.

You may end up having to rebuild the carburetor using a rebuild kit or replacing the carburetor depending on the condition of the carburetor.

Stuck float needle in a Ferris 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 actually stuck. The needle works with the float to keep gas flowing into the bowl. When the needle is stuck, you must rebuild your carburetor.

To temporarily loosen your stuck needle, tap the carburetor with a rubber mallet. A rubber handle on a tool also works well. This may work once or twice, but eventually, you will have to replace the float needle to correctly fix your Ferris carburetor.

Bad Fuel Filter is Leaking Gas on a Ferris Lawn Mower

The fuel filter should be changed out at least annually or when it becomes plugged. If you don’t do this, the plastic can begin to degrade from fuel sitting in the filter.

Old fuel will soften the plastic housing on the fuel filter and begin leaking at the seams. The filter could also have been damaged and cracked causing it to leak.

You must replace a leaking Ferris fuel filter. Be careful replacing a plastic fuel filter. The ends of the filter can become soft and may break off in the fuel line.

To help prevent the filter from leaking in the future, replace it regularly. The fuel filter is essential to keep dirt out of the fuel system which can cause wear on the carburetor and engine.

Bad Fuel Pump is Leaking Gas on a Ferris Lawn Mower

Just like the fuel filter can degrade from old gas, the same is true of your fuel pump. Check the seams of your fuel pump for leaks. Replace the fuel pump with a new one when you find a leak.

Fuel Tank Seam is Leaking Gas on a Ferris Lawn Mower

The fuel tanks used on a Ferris zero-turn or walk-behind mower are made of high-density polyethylene material. These tanks may fail at the seams and begin leaking. It’s best to replace a fuel tank when you find it leaking from the seam.

Fuel Shut-Off Valve is Leaking Gas on a Ferris Lawn Mower

A Ferris lawn mower has a fuel shut-off valve. If you have a zero turn, you most likely have two fuel shut-off valves, one by the left-hand fuel tank and one by the right-hand fuel tank.

Fuel valves are prone to leak over time. Replace it if you find it leaking.

Old Fuel Lines Are Leaking Gas on a Ferris Lawn Mower

As the fuel lines on your Ferris lawn mower age, they will become dry. They may develop cracks and begin leaking gas.

Follow the fuel lines coming out of the fuel tanks. Check the fuel lines, hose connectors, and clamps to ensure there are not any leaks.

Replace fuel lines where you find a leak. Pay attention to the diameter of the fuel line so you purchase the correct replacement hose. It is also good practice to replace the lines that dry and develop cracks before they begin to leak.

When replacing your fuel lines, take a look at the clamps. If your mower has pinch-style clamps, I recommend replacing them with worm gear clamps because they are less likely to puncture the fuel line and cause leaking.

Bad Gas Cap is Leaking Gas on a Ferris Mower

If you’ve gotten this far and can’t find the leak on your Ferris, it’s time to check the gas cap. There is a seal in your Ferris mower’s gas cap that is subject to drying out over time.

When it becomes dry, it no longer seals correctly. Gas sloshes around the fuel tank when you’re operating the mower and can leak out of the cap.

If the mower has been sitting for a while, you may not see any wet spots around the fuel cap area. This is because gas evaporates.

To determine if the seal is bad in the gas cap causing fuel to seep out around the cap, carefully rock your mower back and forth to splash fuel up around the tank cap. Don’t get too aggressive. You don’t want to lose your balance or tip the mower.

If you notice a wet area forming around the fuel cap outside of the tank, replace your cap with a new Ferris gas cap.