Your Gravely Lawn Mower Is Leaking Gas (Solved!)

You may have noticed burnt spots in your lawn from gas leaking from your Gravely lawn mower. Or, you may have noticed a wet spot form under the mower, a strong fuel odor in the air, or excessive fuel consumption. These are all signs your mower may be leaking gas.

A Gravely lawn mower can begin leaking gas from a bad gasket or stuck float on the carburetor. It can also leak gas from the fuel filter, fuel pump, fuel lines, fuel tank, fuel shut-off valve, and gas cap.

Finding the cause of your fuel leak can be tricky, especially when gas evaporates and doesn’t leave a physical wet spot behind by the time you realize you have a fuel leak problem. Follow all safety guidelines outlined in your Gravely owner’s manual.

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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, or knowledge or are not in the condition to perform the repair safely.

7 Places Your Gravely Lawn Mower is Leaking Gas

Carburetor is Leaking Gas on a Gravely Mower

It is common for the carburetor on a lawn mower to begin leaking fuel. This is the place where a small amount of gas is stored after it leaves the fuel tank.

Old gas that sits in your carburetor can begin to form gummy deposits that can cause small components in the carburetor to become stuck and no longer function. There are a few items on the carburetor that should be checked when looking for a fuel leak.

Gasket failure in the carburetor bowl on a Gravely mower

First, look at the bowl on the carburetor. This is located at the bottom of the carburetor and holds a little fuel. Check for any signs of leaking from the gasket that is located between the bowl and the carburetor. This gasket looks like a rubber band.

Gas is prone to leak from the gasket area because of its location in the engine. The gasket is subjected to swings in temperature that puts stress on the gasket. The gasket gets hot when the engine is running and cools down when it is not.

Because of the extreme change in temperatures, the gasket becomes dry and brittle losing its ability to seal properly. If you find a leak 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 your Gravely mower’s carburetor.

Stuck float in a Gravely mower carburetor

Next, check for a leak from the carburetor near the air intake port. If you find a leak, the culprit is most likely a stuck carburetor float. When the float operates correctly, it regulates the amount of fuel allowed into the carburetor bowl.

When the float gets stuck on your Gravely mower, the float can no longer control when the fuel is to stop flowing. Fuel will overflow and leak out of the carburetor.

A leak caused by a stuck float must be fixed by disassembling your carburetor to find and repair the cause of the stuck float.

You may be able to clean your Gravely’s carburetor to free up the float. When inside your carburetor, you may find you need to rebuild or replace your carburetor.

Stuck float needle in a Gravely 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.

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

Fuel Filter is Damaged or Degraded on a Gravely Mower

Old fuel will degrade and soften the plastic housing on the fuel filter. The fuel filter will begin leaking at the seams when this happens.

Replace a fuel filter that is leaking due to an old degraded or damaged filter. Be careful when changing out your filter if the 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 Gravely’s routine service maintenance.

Bad Fuel Pump on a Gravely Mower

Just like the fuel filter can degrade from old gas, 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 Seam Failure on a Gravely Mower

Gravely lawn mower fuel tanks are made with high-density polyethylene material that can begin leaking at the seams. When this happens, it is best to replace your fuel tank.

Fuel Shut-Off Valve on a Gravely Mower

A Gravely lawn mower has a fuel shut-off valve located at the bottom of the fuel tank to stop fuel from flowing through the mower. Fuel valves are prone to leak over time. The fuel shut-off valve must be replaced when a leak is found.

Old Fuel Lines on a Gravely Mower

As the fuel lines on your Gravely mower become older, they will dry out, crack and begin leaking. Check the fuel line coming out of your fuel tank and follow it up to your carburetor.

Check for leaks coming from cracks in the line and from punctures around the hose clamps.

Replace fuel lines where you find a leak. 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 on a Gravely Mower

The seal around your Gravely mower’s gas cap can dry out and no longer seal correctly. Fuel can begin leaking around your gas cap when fuel is sloshed inside the fuel tank when operating your mower.

You may not have noticed a leak in this area because gas evaporates and will not leave any sign of leaking. You may only be left with fumes in the air.

To check for a bad seal on your gas cap, rock your mower back and forth to splash fuel around the gas cap area.

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