You go out to your garage and smell a strong odor of fuel in the air. You’ve identified the smell is coming from your lawn mower. Your gas leak may be significant and you’re left with a pool of gas under your Troy-Bilt mower.

However, most likely the leak is small and hard to find because, by the time you noticed a smell in the air, the fuel has evaporated leaving little evidence of a wet spot.

A Troy-Bilt lawn mower can begin leaking gas from a dirty carburetor with stuck parts or a failing gasket. Leaking gas can also be the result of deteriorating fuel parts including fuel lines, fuel pump, fuel filter, gas tank, and gas cap seal.

Always work in a well-ventilated area. Take all safety precautions when working with fuel and your Troy-Bilt mower.

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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.

Items Causing Your Troy-Bilt Mower to Leak Gas

• Dirty Carburetor
• Failing Carburetor Parts
• Bad Fuel Filter
• Deteriorating Fuel Pump
• Rusted Metal Tank or Seam Failure on Poly Fuel Tank
• Fuel Shut-Off Valve
• Dry or Cracked Fuel Lines
• Cracked Primer Bulb
• Bad Seal in the Gas Cap

Troy-Bilt Carburetor is Leaking Gas

Your carburetor is the item that regulates the amount of air and gas needed to form a combustion. This is the place some fuel is stored once it leaves the fuel tank.

Dirty and old fuel can cause your carburetor to gum up and form deposits that prevent your carburetor from working correctly. Failing parts on your carburetor can cause your Troy-Bilt mower to leak gas.

Gasket failure in the carburetor bowl on your Troy-Bilt Mower

You will find a gasket that seals the carburetor to the carburetor bowl. The gasket looks like a rubber band. Over time, the gasket will become dry and brittle because it is consistently stressed by heat and cold.

Because the gasket is located close to the engine, it heats up when your mower is running and cools down when it is not. When this gasket becomes dry, it loses its ability to seal and will eventually allow gas to leak out of the bowl.

If you find the gasket around the bowl is leaking, you can easily fix it. Begin the repair by shutting off the fuel supply. Use the fuel shut-off valve under your gas tank or, if your mower doesn’t have a valve, use a clamp to clamp the fuel line.

Once the fuel flow has been stopped, remove the screw and remove the carburetor bowl. Have a rag available to catch the remaining fuel in the bowl. Remove the old gasket and place the new one on the bowl. Reinstall the carburetor bowl.

Tighten the screw to hold it all together. Wipe down your carburetor, turn on your fuel supply, and check for any additional leaks from your carburetor.

If you notice more leaks, check your carburetor float and needle. These are common items that can get stuck and cause leaking.

Stuck float in your Troy-Bilt mower’s carburetor

Next, you’re going to look for a leak near the air intake port. A leak in this area may indicate you have a stuck carburetor float.

The float regulates how much gas is allowed to enter the carburetor bowl. When your float stops regulating fuel, gas can continue to flow into the bowl and overflow. Fuel will run out of your carburetor.

If your float 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 the procedures for cleaning the carburetor in this article.

Stuck float needle on your Troy-Bilt Mower

The float needle works with the carburetor float to keep gas flowing into the bowl. The needle can get stuck and may need to be replaced. You can attempt to repair it yourself or take to your local Troy-Bilt dealer to be rebuilt.

To temporarily get your float to become unstuck, you can tap the side of the carburetor gently with the handle end of a hammer, but this may only work a time or two.

Troy-Bilt Fuel Filter is Cracked or Deteriorating Causing a Leak

Fuel can cause degradation in plastics like that used for a Troy-Bilt inline fuel filter. The filter can begin leaking at the seams when your filter deteriorates. It can also leak if the plastic is cracked. A leaking fuel filter needs to be replaced.

Be careful when removing the ends of the inline filter from your fuel lines as the plastic can become soft and break off. You can find a replacement inline fuel filter online or at your local hardware store.

The type of fuel you use in your Troy-Bilt mower and how you store it can affect your fuel system. Read more about the effects of ethanol and the best way to stabilize your gas in my article on Troy-Bilt lawn mower gas.

Bad Troy-Bilt Fuel Pump Can Begin Leaking Gas

Much like the effects fuel can have on your inline fuel filter, the same is true with your Troy-Bilt fuel pump.

Most Troy-Bilt fuel pumps are made of plastic which can deteriorate causing damage internally and leaking through the seams of the plastic. When the fuel pump starts to leak, the pump is no longer able to build pressure. You must replace your fuel pump.

Rusted or Failed Seams on Your Troy-Bilt Fuel Tank Will Begin to Leak

Depending on your Troy-Bilt mower, you will have a metal or high-density polyethylene gas tank.

A metal tank can rust and develop holes causing fuel to leak. You can use a petroleum-resistant epoxy to seal the hole like TankWeld by J-B Weld or replace the tank if a replacement is still available.

Most fuel tanks today are made with high-density polyethylene, but you will still find metal tanks on smaller engines. The seams on these tanks can fail causing the fuel tank to leak. The best solution is to replace your fuel tank with a new tank.

Troy-Bilt Fuel Shut-Off Valve is Prone to Leaking Gas

Many Troy-Bilt mowers use a fuel shut-off valve which is located under your fuel tank. This valve is used to start and stop your fuel supply.

Your shut-off valve may be made of plastic or metal. Both types are prone to leaking gas and should be replaced if you find the valve to be leaking.

Old Troy-Bilt Fuel Lines Can Become Dry and Leak

Eventually, your fuel lines will become dry and cracked. Your fuel lines may begin leaking at the cracks or around the clamps used to secure your fuel lines.

Follow your lines out of the gas tank looking for wet areas on the hose. Pay close attention to the sections of the fuel line that are held on by clamps as these areas are known to leak.

Any cracked fuel lines need to be replaced. This may also be a good time to replace the type of fuel clamps if your mower uses a pinch-style clamp. I like using a worm gear clamp because they are less likely to pinch your lines and cause leaking.

Cracked Primer Bulb Can Begin to Leak Fuel

If your Troy-Bilt mower uses a primer bulb to assist with priming the carburetor, you need to check it for a leak. It may leak if the plastic becomes dry or the bulb is overfilled with fuel.

The area where the primer bulb is attached to the fuel line is also a place that is known to start leaking.

Bad Troy-Bilt Gas Cap Seal Can Cause Leaking

You may or may have not noticed a wet spot forming around your fuel tank cap. Sometimes it can be very hard to spot a bad seal on your gas cap because often the gas evaporates before you see a wet area.

When you smell gas and can’t isolate the area following the steps above, you should check your gas cap.

To determine a bad seal, rock your mower back and forth to splash fuel around the gas cap area. If you develop a wet spot, it is time to replace your Troy-Bilt gas cap.