Why Is My Lawnmower Carburetor Leaking Gas? How Do I Fix A Leaking Lawn Mower Carburetor?

by Lee Safin

A leaking carburetor for a lawnmower can be a pretty annoying issue while the machine is still run. You will have gas straining at the bottom, which will leave you not only a mess, but you will also lose a ton of gas. So, the soonest you fix it, the better it is.

Why is my lawnmower carburetor leaking gas?

One of the most common causes behind the carburetor is leaking gas out is the overflow tube because the floats are stuck or heavily damaged. In addition, if you are using ethanol-containing fuel for a long time, it can also cause your carburetor to leak gas.

Before fixing the gas leaking issue, you want first to find out the main reason behind it. After that, you can implement an effective solution to deal with the problem.

Why Is My Lawnmower Carburetor Leaking Gas? How Do I Fix A Leaking Lawn Mower Carburetor?
Why Is My Lawnmower Carburetor Leaking Gas? How Do I Fix A Leaking Lawn Mower Carburetor?

Why Is My Lawnmower Carburetor Leaking Gas?

Why Is My Lawnmower Carburetor Leaking Gas?
Why Is My Lawnmower Carburetor Leaking Gas?

Do you know the answer to this question: how do you stop a carburetor from leaking gas? For that, you must first determine what caused it.

When are you wondering the question of why is my lawnmower carburetor leaking gas? There could be different causes, which we are going to mention below.

1. Floats Are Stuck Or Damaged

Why Is My Lawnmower Carburetor Leaking Gas - Floats Are Stuck Or Damaged
Why Is My Lawnmower Carburetor Leaking Gas - Floats Are Stuck Or Damaged

Whether the carburetor float has become bad or not, you can test it out. When you tap the float, it should bounce up and down. You can tell how healthy your float is by that.

AUTOLA Carburetors Carbon Dirt Jet Remove Cleaner, 13 Cleaning Wires Set + 10 Cleaning Needles + 5 Nylon Brushes Tool Kit For Welder Carb Chainsaw Spray Guns Torch Tips Firing Hole Stove Burner Holes
AUTOLA Carburetors Carbon Dirt Jet Remove Cleaner, 13 Cleaning Wires Set + 10 Cleaning Needles + 5 Nylon Brushes Tool Kit For Welder Carb Chainsaw Spray Guns Torch Tips Firing Hole Stove Burner Holes

On the other hand, a bad float will be very hard to push down, and it will not rebound quite as good as the healthy float does.

2. Ethanol-Containing Fuel

Why Is My Lawnmower Carburetor Leaking Gas - Ethanol-Containing Fuel
Why Is My Lawnmower Carburetor Leaking Gas - Ethanol-Containing Fuel

If your mower fuel contains 10-15% ethanol, it will harm the various parts of the carburetor. You should remember that your lawnmower carburetor is not designed to use this type of ethanol-containing fuel. Using this fuel for a long time will disrupt the functionality and will cause leakage issues.

So, these are two primary reasons for this query: why is my lawnmower leaking fuel? Knowing them helps you take immediate action.

Read More – How Much Oil Capacity Does Honda 160cc Lawn Mower Can Has?

Why Is Gas Coming Out Of My Carburetor?

A few factors may be the culprit for this issue. We are going to outline all the possible causes step-by-step to answer the question of why is gas coming out of my carburetor? Inspecting each part of the carburetor separator will help you to find the root cause of it.

Step 1 – Make Sure The Fuel Line is Connected

Why Is Gas Coming Out Of My Carburetor?
Why Is Gas Coming Out Of My Carburetor?

First of all, you want to make sure the fuel line is connected to the carburetor correctly. The location of the gas line should be on the brass nipple, which is located on the carburetor side.

Step 2 – It May be a Vapor Locking Issue

Why Is Gas Coming Out Of My Carburetor - It May Be A Vapor Locking Issue
Why Is Gas Coming Out Of My Carburetor - It May Be A Vapor Locking Issue

Check if the problem is fixed by taking the gas cap off. It may be a Vapor locking issue that mainly happens when the gas cap is not venting properly.

Keep the gas cap off for 5-10 minutes and examine if the problem still persists. If yes, move to the following step.

Step 3 – Inspect Wheather The Gas Line is Spilled or Not

Why Is Gas Coming Out Of My Carburetor - Inspect Wheather The Gas Line Is Spilled Or Not
Why Is Gas Coming Out Of My Carburetor - Inspect Wheather The Gas Line Is Spilled Or Not

Inspect whether the gas line is spilled or not. The gas line might be in trouble if a spilled issue has occurred beneath the gas tank, located to the carburetor side.

You must attentively examine the black gas line for splits or cracks after removing it. Changing the gas line is necessary if it is split.

Step 4 – Any Stuck Issues For The Carburetor Flot?

Why Is Gas Coming Out Of My Carburetor - Any Stuck Issues For The Carburetor Flot?
Why Is Gas Coming Out Of My Carburetor - Any Stuck Issues For The Carburetor Flot?

The next job is figuring out if any stuck issues for the carburetor float. We have already discussed how to deal with a stuck carburetor float. Make sure to follow it correctly to solve the problem easily.

Step 5 – The Might be Dirt in the Carburetor

Why Is Gas Coming Out Of My Carburetor - The Might Be Dirt In The Carburetor
Why Is Gas Coming Out Of My Carburetor - The Might Be Dirt In The Carburetor

If the steps outlined above did not help, there might be dirt in the carburetor. You need to clean the carburetor as early as possible. We will guide how to clean a carburetor in another section.

In addition, a fresh gas/fuel line needs to install if your mower contains an in-line fuel filter. If your mower doesn’t have any in-line fuel filter, you can grab it from a nearby shop.

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

Step 6 – Take Professional Help

After cleaning the carburetor, it should be free from the leaking gas issue. If not, repairs should be done in a garage nearby.

Hopefully, you have learned all probable causes of the question of why is gas coming out of my carburetor?

Can You Clean Lawn Mower Carburetor Without Removing?

The carburetor of a lawnmower needs to be inspected regularly. If you don’t watch out for it regularly, the air filters can become clogged with lawn debris. If the carburetor is not functioning properly, you can run the machine smoothly. Several unwanted issues will pop up, making your mowing task tiresome.

Can you clean the lawnmower carburetor without removing it?

Yes, you can clean a lawnmower carburetor without removing it. But, cleaning it after removal will be more effective.  

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

In order to clean the lawnmower carburetor while it is on the machine, you just need to remove the bowls at the bottom of the carburetor and use a good quality carburetor cleaner aerosol spray to clean it thoroughly.

So, you have a clear idea of what needs to be done about the question: can you clean lawn mower carburetor without removing it?

Read More – Why Is My Lawnmower Making Loud Noise? How To Fix A Noisy Lawnmower?

How Do I Fix A Leaking Lawn Mower Carburetor?

You have already learned about the question: why is my lawnmower carburetor leaking gas? Fixing a leaking lawn mower carburetor is not as hard as you think. Once you follow the right method, you can deal with it of your own.

So, you must be wondering about the question: how do I fix a leaking lawn mower carburetor? Right? No worries; follow these solutions to fix it.

Solution 1 – Get Your Carburetor Float Unstuck

Why Is Gas Coming Out Of My Carburetor - Get Your Carburetor Float Unstuck
Why Is Gas Coming Out Of My Carburetor - Get Your Carburetor Float Unstuck

So, the first convenient way to fix your carburetor from leaking gas is to get your carburetor float unstuck.

The easiest way to do it is to locate your overflow tube connected to the bottom of the carburetor.

You will notice the float valve is stuck open where the gas is draining out. Then, what you’re going to want to do is to remove all the gas from the bottom of that float valve first.

By coming over to the other side of the carburetor, you’re going to turn your gas off so that way there’s no more gas flow to the carburetor.

Then, you will locate your overflow screw, which is a little screw at the bottom of the carburetor.  After that, just take a flathead screwdriver and loosen it up all the way. Make sure the gas is off while the gas is draining out. Since you cut off the supply gas in the carburetor, it will not keep draining out.

You can use a cup to catch all the gas coming out the bottom because you don’t want the gas to go all over the ground. When the task is completed, you can put it back in the gas tank.

Briggs & Stratton 799863 Fuel Tank Replaces 694260/698110/695736/697779
Briggs & Stratton 799863 Fuel Tank Replaces 694260/698110/695736/697779

Next, you will take some compressed air and just blow it up the drain hose. What that compressed air will do is hopefully travel up through the line and contact the stuck float and essentially break it free.

It will most likely remove any dirt or debris that it’s keeping that float stuck open. Hopefully, it works. It is the easiest way to do it.

Don’t forget to tighten this overflow screw back, turn on the gas and see if it drains out.

Solution 2 – Clean The Carburetor

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

If the

does not work, you need to take apart the carburetor clean it. And try to figure out what dirt and debris are keeping that float valve stuck open. Ensure to clean the carburetor’s internal parts thoroughly so that no dirt, grease, or grime is visible.

Solution 3 – Your Float Valve Has Gone Bad

Is the problem still persisting?

If yes, you can see the problem is not that the carburetor is dirty because you have obviously cleaned it.

The last probably reason could be your float valve has gone bad. The float valve is easily accessible from a nearby shop. Replacing is also easy. You just slide this pinout, and the float comes off. Take an intact float valve, just slide it in, and put it back together.

Panari 398188 Carburetor Float Valve Needle Seat Kit Replacement For All Max Quantum 5HP And 6HP Vertical Engines (Pack Of 6)
Panari 398188 Carburetor Float Valve Needle Seat Kit Replacement For All Max Quantum 5HP And 6HP Vertical Engines (Pack Of 6)

That’s the three effective solutions to this query: how do I fix a leaking lawn mower carburetor?

How Do You Clean A Carburetor?

If you overlook the regular inspection of your mower, you may end up changing the worn-out parts of your mower. The perfect working condition of a lawnmower depends on keeping the carburetor clean.

So, how do you clean a carburetor? Do you want to clean it without removing the carburetor or after removing it? No doubt, cleaning the carburetor after removing it from the machine is the best solution.

However, some people prefer to clean it without removing the carburetor. Here we are mentioning step by step how to clean a carburetor without removing it.

Serial No. Task
1 Shut down the mower
2 Check out the air filters
3 Inspect all connections to the carburetor
4 Clean the carburetor

Step 1 – Shut Down The Mower

Have you used the mower a while ago? If yes, turn off the machine and let it cool down for several minutes before cleaning the carburetor.

Step 2 – Check Out The Air Filters

Briggs & Stratton 491588S Flat Air Filter Cartridge
Briggs & Stratton 491588S Flat Air Filter Cartridge

Before diving into the cleanup procedure, you want to check out any clog-up issue inside the air filter. Make sure the air filter is free from dust, debris, or any other unwanted substances.

Cleaning is necessary to eliminate the clogging-up issue. The mower will only produce black smoke while operating if the air filter has any problem.

Step 3 – Inspect All Connections To The Carburetor

In order to ensure all the connected components from the carburetor to mower are working perfectly, you want to clean them all properly.

Regular check-up is necessary because any part of the machine can be damaged over time. If you inspect and clean them regularly, they will remain in good condition with a long lifespan. So, maintenance is the key!

Step 4 – Clean The Carburetor

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

Make sure you have removed all the connections from the carburetor and opened the air filters. By removing the cover, you can see inside the carburetor and clean it more easily.

The clog-up issue inside the carburetor occurs from lots of things such as tiny grass, dirt, grease, grime, etc. The carburetor won’t function correctly without cleaning it regularly. The component fails to achieve a perfect ratio of fuel and air. It may turn off the lawnmower completely.

As an alternative, you can also apply clean carb spray or similar products to clean the carburetor deeply. However, if the engine is not running, spraying the carburetor won’t work. Cleaning is impossible without propulsion.

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

In that case, you want to first switch on the carburetor and spray the solution on it. The solvent will help to remove all the unwanted dirty substances from the component.

After cleaning all the components appropriately, you want to put them back in their place and start the engine. Try out if the mower is working properly.

Regular inspection is necessary. That’s why you want to test out the machine performance in every season. Don’t forget to give a check on the spark plugs too.

How To Clean The Lawnmower Carburetor After Removing It?

You have already learned how to clean a carburetor without removing it. Now, let’s know how to clean a carburetor after removing it.

In order to clean the carburetor deeply, you need an effective cleaner. Make sure the cleaner is safe for the machine parts, non-corrosive, and biodegradable.

A wide range of solutions can be found on the market. You can choose the CRC Carb & Choke Cleaner as many gardeners recommended it.

Before diving into the cleaning procedure, you want to follow the manufacturer’s instruction manuals. If the mower has a warranty, violating their terms & conditions will make the warranty period invalid.

First, let get an overview of the cleaning process through a table.

Serial No. Task
1 Solution mixture
2 Cleaning the air filter
3 Detach the carburetor
4 Detach the carburetor float
5 Detach other detachable parts
6 Soak and clean the machine parts
7 Rinse and dry
8 Put the parts in their place

Step 1 — Solution Mixture

Gumout 800002231 Carb And Choke Cleaner, 14 Oz.
Gumout 800002231 Carb And Choke Cleaner, 14 Oz.

Take a large container and pour out some CRC Carb & Choke Cleaner inside while following the mixture 1:3 (cleaner: water).

Step 2 — Cleaning The Air Filter

No products found.

No products found.

Cleaning up the air filter is essential before the carburetor. The reason is that you want to make sure the air filter is free from any clogging-up issue.

If there are blockage issues inside the air filter, air will not come freely, and black smoke may be emitted from the exhaust.

In that case, remove all the connections from the air filter and use compressed air to eliminate all the dust from the air filter.

Step 3 — Detach The Carburetor

Remove the carburetor from the lawnmower and all the connections from the machine too. Also, take off any cover or guard from the part.

Use compressed air to blow out all the unnecessary substances from the carburetor. Be careful while using compressed air as you may disconnect the wire of the machine.

Step 4 —Detach The Carburetor Float

After removing the carburetor, you want to remove the float nuts. Make sure you don’t spill the existing gas from the fuel tank.

GFN Nut Assembly - 1650 Brine Nut And 2310 Float Nut
GFN Nut Assembly - 1650 Brine Nut And 2310 Float Nut

Plus, take out the pin at the pivot point of the float and set it aside. Finally, detach the float from the casing by pulling it straight up.

Step 5 —Detach Other Detachable Parts

In order to clean the carburetor thoroughly, it is better to detach other detachable parts from the carburetor area.

Step 6 —Soak And Clean The Machine Parts

Descaler (2 Pack, 2 Uses Per Bottle) - Made In The USA - Universal Descaling Solution For Keurig, Nespresso, Delonghi And All Single Use Coffee And Espresso Machines
Descaler (2 Pack, 2 Uses Per Bottle) - Made In The USA - Universal Descaling Solution For Keurig, Nespresso, Delonghi And All Single Use Coffee And Espresso Machines

After detaching all the detachable parts from the machine, but the components inside the mixture of CRC Carb & Choke Cleaner.

Keep them in this condition for 10-15 minutes and clean the parts gently with a soft brush. Make sure to clean the small components too.

Step 7 —Rinse And Dry

After cleaning the machine parts properly, rinse them in a container of fresh water. Allow them to dry. If necessary, especially for small pieces, use compressed air to eliminate any additional dampness.

Step 8 —Put The Parts In Their Place

Once the parts become fully dry, you want to put them back in their original place. Make sure you install them correctly. No mistakes! Connect all the wires and clamps appropriately.

Hopefully, you have gotten a clear idea about this question: How do you clean a carburetor?

When To Take Professional Help?

Figuring the reason for this question is necessary: Why is my lawnmower leaking fuel?

Is your lawnmower still not working smoothly after cleaning the carburetor thoroughly? If yes, the only alternative is to take the machine to a nearby shop.

Professional people are there for you to repair your mower. They will first figure out the kind of issue your mower is having and fix it based on it.

Closing Points

Are you still wondering about this common question: why is my lawnmower carburetor leaking gas?

A lawnmower carburetor shows a leaking gas issue when the overflow gets stuck or becomes damaged.

Make sure you take care of your lawnmower carburetor and clean the component regularly.

Follow our instructions to clean the carburetor without removing it or after removing it. Hopefully, you have also learned about this query from our solution: how do you stop a carburetor from leaking gas?

Last update on 2023-01-28 / Affiliate links / Images from Amazon Product Advertising API

About Lee Safin

Lee Safin was born near Sacramento, California on a prune growing farm. His parents were immigrants from Russia who had fled the Bolshevik Revolution. They were determined to give their children a better life than they had known. Education was the key for Lee and his siblings, so they could make their own way in the world. Lee attended five universities, where he studied plant sciences and soil technologies. He also has many years of experience in the U.S. Department of Agriculture as a commercial fertilizer formulator.

Thoughts on "Why Is My Lawnmower Carburetor Leaking Gas? How Do I Fix A Leaking Lawn Mower Carburetor?"

Get FREE Gardening Gifts now. Or latest free toolsets from our best collections.

Disable Ad block to get all the secrets. Once done, hit any button below