Mower carburetor leaking fuel. How to Fix a Go-Kart Carburetor That Is Leaking Gas

Reasons A Generator Carburetor is Leaking Gas How to Fix

If you have smelled an odor of gasoline in your garage and followed your nose to your generator, you’ll likely see that the source of the leak is around the carburetor.

The generator is a contraption that can be intimidating to anyone who hasn’t disassembled and reassembled one. When I got into small engine repair about 7 years ago as a side hobby, I was so confused by the carburetor and what everything did on it.

As a general rule, a generator’s carburetor will leak gas due to an improper seal between the float needle and the seat, damaged gaskets around or under the carburetor bowl, or the bolt at the bottom of the bowl is not tightened properly.

  • Bowl Gasket is Cracked, Pinched, Split
  • Drain Screw Gasket is Cracked, or Not Tightened Properly
  • Bowl Bolt Gasket is Cracked, or Not Tightened Properly
  • Fuel lines are Cracked
  • Fuel shutoff solenoid is Leaking
  • Float needle not seating properly (Fuel Leaking out of the Air Filter or Fuel in your Oil)

I will guide you through the 6 primary reasons that you might be finding fuel leaking around your generator and what you can do to fix them.

Before you FOCUS all of your attention on the carburetor itself, dry everything with a rag first and verify that you do not have a leaky gas tank or a rotted fuel line at the gas tank. If this occurs, gas can run down the outside of the fuel line to the carburetor and throw you off course.

With that being said, let’s dive in!

⬇⬇⬇ Here’s a video I made to guide you through the common problem of why a carburetor leaks gas from the air filter (or throat of the carburetor) and how to fix it. I’ve had this happen to lots of small engines that I’ve repaired over the last 7 years. If your air filter smells of gas, or if your oil’s dipstick smells like gas, then this video is for you! ⬇⬇⬇

The black ring is the bowl gasket for the carburetor.

In either case, you will need to shut off the fuel shut off valve and find a suitable container to drain some fuel into. Grab a 10 mm wrench or socket and remove the main bolt which is located on the very bottom and center of the bowl.

With the bolt removed, gasoline will pour out until the bowl empties. It shouldn’t be much.

Once the gasoline is drained out, pull the bowl off and inspect the gasket. If it has any cracks, has dried out, is split, or has a permanent pinch in it then you will need to replace this gasket. Thankfully they’re not expensive. You might as well buy two while you’re at it and keep a spare one inside and out of the sun. My wrench is on the drain bolt. The bolt that holds the carburetor bowl in place is right behind it.

If you verified that the bolt is tightened properly, shut off the fuel valve, and place an appropriate container underneath the carburetor for catching gasoline. Use that 10 mm wrench or socket to remove the drain screw. Inspect the gasket which is usually made out of fibrous, cardboard-like material. Inspect it and make sure that it doesn’t have any tears. If it’s bad it will need to be replaced.

In a pinch, I’ve actually used a piece of a shoebox as a replacement on my snowblower (it happened to be the same relative thickness as the fiber washer/gasket. I just took the old one off, dried it, laid it on a shoebox lid, traced the outline and cut it out. This worked until I was able to get a replacement. Who knows how long it would have lasted.

You might also be able to use a plastic milk jug as your temporary replacement.

Bowl Bolt Gasket is Cracked or Not Tightened Properly

Drain bolt on the bottom, the bowl bolt is right above it. The gaskets are a pinkish red color,

This one is similar to the one above. First, verify that the bolt is indeed tightened properly with a 10 mm wrench or socket. If it’s snug and then turned about and 8th of a turn more and still leaking then you need to drain out the gasoline in the bowl by shutting off the fuel valve and then use a 10 mm socket or wrench to remove the bolt at the bottom of the bowl.

Once the bolt is pulled out the gasoline will flow through the bottom and the bowl will likely stay in place if it had a good seal.

Check the integrity of a gasket which is often made of fibrous cardboard-like material. If it’s torn then replace it. And like I mentioned in the above step, you can dry off the damaged gasket, lay it on a piece of similar thickness cardboard (or milk jug), trace it, and cut it out as a replacement.

It’s still in your best interest to replace it with a proper gasket when you’re able to but don’t let a small leak like that stop you from having power in an emergency. Remember, the gasoline in the bowl is not pressurized.

Fuel Lines are Cracked

Fuel lines will become dry rot with time. This is especially true if you use ethanol-based fuel and let it sit in storage. They will often crack at the points where they join up to something as that is where the fuel lines are stretched slightly.

Investigate for any cracks and if you see them I recommend replacing all of your fuel lines at once if you have the time for it. With one cracked, the others are sure to follow. Black fuel line running from the white gas tank to the carburetor behind the air filter assembly.

When doing this it’s probably easiest to drain out all of the fuel out of your tank if it hasn’t already leaked out already. You can use an inexpensive hand pump, like this one on Amazon, or simply open up the drain bolt on your carburetor and let the fuel run through the open fuel valve through the carburetor and into a container.

After that, remove the fuel lines from where they are connected with a flat head screwdriver and a pair of pliers if necessary. You can reuse all of the hose clamps that were on the fuel lines beforehand. Slide the hose clamp on the new fuel line first and move it up a few inches. Then press the fuel line onto the fuel stem, then use a pair of pliers to move the clamp back down and place it over where the fuel line connects to the stem to hold it in place.

Fuel Shut-off Solenoid is Leaking

If your generator is equipped with a carburetor that has a fuel shut-off solenoid, you might notice a gas leak at that location.

A fuel shutoff solenoid is attached to the bottom of the carburetor bowl and is activated by electricity passing through the wires which causes a magnet to retract a plug that blocks the fuel jet when the generator is running or go back in place with a spring when the engine is turned off.

This prevents after-firing if the generator were to be stopped abruptly under a heavy load. After-firing is caused when you abruptly stop an engine while under load and the crankshaft is still spinning (at 3,600 rpms and coasting to zero). This causes the combustion chamber to keep sucking in air and fuel at a Rapid rate for a few seconds but doesn’t ignite it with the spark plug since the engine is off. The unburnt air and fuel mix is exhausted and combusts on the hot metal of your exhaust which creates a loud bang.

Typically, a fuel shutoff solenoid leaks at the gasket that is between the bottom of the bowl and the solenoid itself. In this case, you can replace it with a new gasket. Less common is a solenoid that is leaking from the bottom. If this is the case, you will need to have it replaced. It simply unscrews with an appropriately sized wrench and screws back in after detaching the wire connection above the carburetor.

How To Fix A Briggs Or Tecumseh Lawn Mower That Leaks Gas From The Carburetor

Float Needle Not Seating Properly (Fuel Leaking Out of the Air Filter Assembly or Fuel Mixed in with Oil)

If you notice gasoline coming out of your air filter assembly or if you notice that when you check your oil it gushes out and/or smells like gasoline, then you have a float needle in your carburetor that is not seating properly to prevent unwanted gasoline from entering the carburetor.

Like water, or any other liquid for that matter, gasoline will try to seek its own level. When you have a fuel tank that is above the carburetor then the carburetor is gravity fed. The purpose of the float in the carburetor bowl is to raise up as the gasoline pours in and then close a needle valve when the float (level of gas) reaches a certain point.

It’s the same concept as your toilet and is why the water tank above your toilet bowl doesn’t overflow as its being refilled after a flush.

If your float needle is not creating a perfect seal, then gasoline will continue to pour in. Since it will seek its own level (the level of the gas tank from which it came) it will fill the bowl of the carburetor completely. Then it will seep up the jets and orifices of the carburetor until it reaches the throat or venturi tube (where your choke and throttle butterfly valves are).

Once there, it will flow either out towards the air filter assembly or into your combustion chamber or both, depending on gravity and how level your generator is.

If gasoline enters the combustion chamber it will gradually seep past the rings on the piston and fall down into your crankcase where it will mix with your oil.

Robert lives in central Michigan and enjoys running, woodworking, and fixing up small engines.

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One of the first things to cross everyone’s mind is does the water still work when the power goes out. Water makes hydration, personal hygiene, cooking, cleaning, and waste removal all.

Power outages are an inevitable part of life, often occurring during severe weather conditions or due to technical issues with the electricity supply. During these times, it’s essential to know how.

About Me

Hi! I’m Robert and this blog started with my journey of learning about battery banks, generators, and power outage preparations. I’ve been an avid hobbyist in these fields for over 7 years and I enjoy sharing what I’ve learned in a way that’s geared for beginners and those just getting their foot in the door with small engine repair and prepping. I’ve been doing maintenance and handyman work for the last several years and I’ll be including little home and garage tips and tricks that I learn along the way as well. Thanks for stopping by!

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How to Fix a Go-Kart Carburetor That Is Leaking Gas

Spotting a gas or fuel leak from a carburetor is a sight that no go-kart racer likes to see. While a leaking carburetor is relatively rare compared to other things that can go wrong with your go-kart, it’s something that you should definitely fix immediately. In this guide, I’ll be teaching you how to fix a go-kart carburetor that is leaking gas.

You’ll notice the gas flowing into the intake manifold or out of your carburetor. There are five common reasons for a go-kart carburetor leaking gas and you can repair it by fixing a stuck carburetor float, unclogging the jets, repairing the broken carburetor float bowl gasket, or fixing a loose or torn gas line connection.

Leaving your carburetor in a leaking state can cause further damage down the road and will also likely lead to erratic idling, delayed starting, stalling and even poor fuel economy.

How Does a Go-Kart Carburetor Work

Before we go through the potential issues that may affect your carburetor and how to fix them, it’s important that you understand how a go-kart carburetor works and what the internal components are. If you’re already familiar with this topic, feel free to skip to the next section of this guide.

A go-kart carburetor or carb is a mechanical device that is attached to the engine and mixes air and fuel into an optimal ratio before it’s pumped into the engine. It takes in filtered air from one valve and fuel from the other, in order to mix it.

An optimally configured carburetor will not only increase the engine performance but also increase your fuel economy. This mechanical device consists of several components that you need to be aware of, so that you’ll know which parts it may be affecting and need to be cleaned or replaced when fixing it.

Parts You’ll Need to Know

  • Fuel Inlet (fuel into carb)
  • Air Intake (air into carb)
  • Float Bowl
  • Float Bowl Drain Screw

List of Potential Carburetor Gas Leak Issues

Now that you understand how a carburetor works and what the most important parts are, it’s time to look at the potential issues for gas leak and how to fix them.

Stuck Carburetor Float

Relevant Parts

A stuck carburetor float is by far the most common reason why a carburetor can leak gas. While it mostly causes a delayed engine start or an engine stall, it can also lead to fuel leaks. When you open the go-kart carburetor and detach the float bowl, you’ll see that the float doesn’t move up or down easily.

If that’s the case, then your carburetor float is stuck and you’ll need to clean the entire carburetor and possibly replace the float valve needle. The float valve needle is located on top of the float valve and enables the float to move up and down. If the needle is stuck, that also means that the float won’t be able to move.

Thoroughly cleaning the carburetor float, float valve needle and float pin should allow the float to move freely again. If that isn’t the case, then you’ll need to see which of the three parts is defective and replace it accordingly.

mower, carburetor, leaking, fuel, go-kart

There are a few things that you’ll need to check and do, in order to fix a stuck carburetor float. Below is a step-by-step guide for this.

Steps to fix a stuck float:

  • Remove the carburetor from your go-kart
  • Remove the float bowl from the carburetor
  • Test if the float is stuck or obstructed
  • Remove the float pin
  • Remove the float
  • Remove the float valve needle
  • Thoroughly clean float, float pin and float valve needle
  • Rebuild lower section of carburetor and test float mechanism
  • Reassemble the carburetor

Top Reasons Lawn Mower Leaking Gas — Lawn Mower Troubleshooting

Clogged Carburetor Jet

Another common issue that can cause a go-kart carburetor to leak gas is a clogged jet. There are two jets that you need to be aware of. After detaching the carburetor and opening it, you’ll be able to spot both of the jets easily.

The location of the main jet is inside the float bowl. It’s the larger of the two jets and is responsible for supplying the carburetor with the required fuel. You’ll be able to identify them easily as their made of brass. The main jets kick in when the throttle is activated (60 – 100% range).

The other jet is called the pilot jet and has the same function but activates when idling. You’ll need to make sure that both jets are not obstructed or clogged. You’ll need to remove them. Give both of the brass jets a thorough clean in an ultrasonic cleaner with a cleaner solution or vinegar. If you find that the jets are no longer good for use, then simply replace them.

mower, carburetor, leaking, fuel, go-kart

Steps to fix clogged carburetor Jets:

  • Remove the carburetor from your go-kart
  • Remove the float bowl from the carburetor
  • Remove the pilot and main jet
  • Thoroughly clean jets and remove dirt and debris
  • Test if jets are unclogged
  • Reassemble pilot and main jet
  • Reassemble the carburetor
  • Information: How to Clean a Go-Kart Carburetor (Step-by-Step Guide)

Broken Carburetor Float Bowl Gasket

Relevant Parts

When you detach the float bowl from the carburetor, you’ll notice that there is a gasket or an o-ring wedged in between the two components. The float bowl gasket acts as a sealant, which prevents air or fuel to escape from the carburetor. There are many gaskets on a carburetor, but the most common gasket that can break is between the float bowl and carburetor.

Due to wear and tear, the float bowl gasket can break or crack making it no longer airtight. This means that gas may seep out the sides. You’ll be able to notice this if you see that the carburetor is leaking gas from the side, where the float bowl connects to the carburetor.

Unfortunately, once a float bowl gasket is broken it can’t be fixed. The good news is that you can simply replace it with a new one, as they’re very affordable and easy to slot in.

Steps to fix a broken carburetor float bowl gasket:

mower, carburetor, leaking, fuel, go-kart
  • Remove the carburetor from your go-kart
  • Remove the float bowl from the carburetor
  • Remove the float bowl gasket
  • Insert the new float bowl gasket
  • Reassemble the carburetor

Loose Fuel Line Connection

Relevant Parts

The first place you should look at if you have a gas leak are the fuel lines that are running into the carburetor. Regular wear can cause certain connections to loosen on the carburetor and the first point you should inspect is the fuel inlet.

The fuel line is connected to the fuel inlet of the carburetor, as it transports the fuel from the fuel tank into the carburetor. The fuel line is connected to the fuel inlet via a clamp. If the clamp comes loose you can sometimes see gas leaking out of the fuel line onto the carburetor. While it may look like the leak is coming from the carburetor, it may actually come from a loose fuel line connection instead.

If the clamp is worn, replace it with a new one. They are relatively inexpensive and can easily be replaced. If the clamp has eaten into the fuel line and the end of the fuel line is damaged, you can cut the damaged piece off or replace the fuel line entirely.

Steps to fix a loose fuel line connection

  • Inspect the fuel line connection
  • If the fuel line is loose, remove fuel line clamp
  • If the clamp is damaged, replace it with a new one
  • If the fuel line is damaged, cut off or replace it entirely
  • Reattached the fuel line to fuel inlet on the carburetor

Torn Gas Line

A torn fuel line can also cause the fuel to seep on to the carburetor, making it seem like the leak is from the carburetor itself. If you see that the leak it’s coming from the carburetor, check the fuel lines from the fuel tank into the fuel filter and the fuel line from the fuel filter to the fuel inlet on the carburetor.A tear in one of the fuel lines will be obvious and you’ll need to fix this by simply disconnecting the fuel line and replacing it with a new one. This should be a quick fix and will only take you a few minutes.

Steps to fix a torn fuel line

  • Inspect the fuel line between the fuel tank and fuel filter
  • Inspect the fuel line between the fuel filter and the fuel inlet
  • Remove the damaged fuel line
  • Replace it with a new fuel line

What Causes Gas to Get in Oil in Lawn Mower?

There are a few things that could cause gas to get in oil in a lawn mower. One possibility is that the gas cap wasn’t tightened properly after refueling. If the gas cap isn’t tight, gas can seep into the oil and cause it to become thick and cloudy. Another possibility is that there’s a crack in the engine’s cylinder head. If this is the case, gas can leak into the engine’s oil and contaminate it.

What Is Gas in Oil?

Gas in oil is a common issue that can occur in lawn mowers. This happens when the gasoline and oil mixture does not combust properly and creates a gas build-up. When this gas builds up it can cause the engine to stall or even worse, it can cause an explosion.

There are a few things that you can do to help avoid this issue. Make sure that you are using the correct oil and gasoline mix for your lawn mower. You should also check the air filter regularly and replace it when needed. Finally, make sure that you are cleaning out the mower regularly so that there is no build-up of grass or debris.

What Happens if Gas Gets Into the Engine Oil?

Gasoline is a volatile liquid that can easily vaporize and ignite. When it gets into the engine oil, it can cause the oil to become very thick and unable to lubricate the moving parts of the engine. This can lead to extensive damage to the engine and may even cause it to seize up completely.

How Can You Tell If Gas Is Mixed With Oil?

If you’re not sure if the fuel in your lawn mower is gasoline or oil, there are a few ways to check. One way is to shake the container. If it’s gasoline, it will be more fluid and move around more easily than oil.

Another way to tell is to look at the color. Gasoline is usually clear or light yellow, while oil is darker. You can also smell them. Gasoline has a characteristic smell of fumes, while oil has a more earthy smell.

Possible Causes of Gas in Oil

If your engine isn’t running right, it can cause gas to enter the oil. Another possible cause of gas in the oil is a leaky carburetor. When the carburetor leaks, it allows fuel to mix with the engine oil. This can contaminate the oil and cause problems with the engine.

If you’re using a lawn mower that runs on gasoline, there’s also a chance that you’re breathing in these pollutants. Carbon monoxide is a colorless, odorless gas, so you may not even be aware of how dangerous it can be.

Bad Gas Cap

A loose gas cap can cause gas to evaporate, which means you’re losing fuel and money. In fact, a bad gas cap is the number one reason for gasoline in engine oil. A bad gas cap can also cause your engine to run rough and pollute the environment.

So make sure your gas cap is tightened securely every time you fill up your tank. If you need a new gas cap, be sure to get one that fits your vehicle properly.

Incompatible Oil and Gas

If you’ve ever pulled your car into a gas station to fill up and noticed that your tank is already full of gasoline, you’ve probably encountered the problem of incompatible oil and gas. This happens when two different types of fuel are put into the same container, and it can cause all sorts of issues. One such issue is that gas can start to evaporate out of the oil, leaving you with a tank full of useless liquid.

This problem is particularly common with lawn mowers. Many people try to save money by using gasoline instead of buying the more expensive oil specifically made for lawn mowers. However, this can often lead to problems. Gasoline is a volatile substance, which means that it evaporates quickly.

Carburetor Problems

In small engine carburetors, the fuel/air mixture is regulated by a throttle valve. The throttle valve is opened by the throttle linkage, which is connected to the accelerator pedal on the vehicle or to the hand lever on lawn mowers. When the accelerator pedal or hand lever is depressed, it opens the throttle valve and allows more air into the carburetor. This increases the speed of the engine and causes more gasoline to be drawn into the cylinders.

If there is too much gasoline in the cylinders, it can escape past the piston rings and enter into the crankcase where it will mix with the engine oil.

Dirty Air Filter

If you have been experiencing gas in your oil, it is likely that your air filter is dirty. A dirty air filter will restrict the amount of air that can flow into the engine. This will cause the engine to run rich, which will result in gas in the oil. The best way to prevent this is to clean or replace the air filter on a regular basis.

How to fix it:

When your lawn mower starts to sputter and die, the problem may not be the engine at all. It’s possible that you have gas in your oil. This is a common issue with small engines, and it’s easy to fix. Just follow these steps:

Shut off the engine and wait for it to cool down completely.

Drain the oil from the engine by unscrewing the drain plug on the bottom of the crankcase.

Clean up any spilled oil with a rag or paper towel.

Add fresh oil to the engine according to the manufacturer’s recommendations.

Start up the engine and check for leaks.


Will Gas Oil Mix Hurt My Lawn Mower?

Gasoline and oil are two of the most important items for your lawn mower. If you do not have enough oil in your lawn mower, it will not run. If you put the wrong kind of oil in your lawn mower, it could damage the engine.

Will Oil in Gas Harm Engine?

Gasoline engines are designed to run on a mixture of gasoline and air. If the gasoline has oil in it, it will not harm the engine, but it will not run as well. The oil in the gasoline will make the engine run a little bit richer than it is supposed to, which means that it will not get as good of gas mileage and it will produce more emissions.


In conclusion, there are several things that can cause gas to get in the oil of a lawn mower. The main causes are a bad gasket, a cracked engine, or a leak in the fuel line. If your lawn mower is having this problem, you will need to take it to a mechanic to have it fixed.

Desmond J. Hernandez

I’m a lawn mowing expert and gardening enthusiast. I started my own lawn care business in college and have been doing it ever since. I love taking care of lawns and gardens, and I’m always looking for new ways to improve my skills. I’m also a big fan of composting and using natural fertilizers.

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