How to Clean a Lawnmower Fuel Line?


When your lawnmower does not start, it can be a real mood destroyer. Similar to when the mower starts but stops running after a few minutes. There could be many possible reasons behind these problems. A a faulty spark plug, no gas or bad gas, oil-related problems, a carburetor issue, a defective starter, or a dirty and clogged fuel line. In this blog post, we will explain what to do when the fuel line is the cause of the problem. In gas mowers, the fuel line connects the gas tank with the carburetor. A dirty or clogged fuel line means a disruption in the fuel supply and problems with starting or running. The fuel line is one of the most critical fuel system components and works together with the fuel filter. This blog post will show you how to clean the fuel line and the components connected to it. Most of the work is fairly simple and does not take a lot of time.

How to clean the fuel line of your gas mower:

Locate the fuel valve and turn it off. If there is not fuel valve, empty the fuel tank. Empty the fuel line after disconnecting it from the carburetor. Use a flashlight to check for holes, dirt, and debris in the fuel line. Use a fuel cleaner to clean the dirty fuel line. If that does not help you have to replace the fuel line. Check the filters and vents for any dirt and debris and clean if needed.

This blog post will show you how to clean the individual components of a gas mower’s fuel system in more detail.

Small Engine Fuel system:

The engines of most gas mowers can be regarded as small engines. Most small engines have similar fuel systems, only the location of the components will differ from type to type. The job of a fuel system is to store fuel and deliver it to the carburetor. The carburetor prepares the fuel-air mixture, also called power charge, to the combustion chamber, where the mixture is compressed and combusted to produce power.

It is quite common for small engines’ fuel systems to become dirty and clogged after extended use. When the fuel system becomes clogged, the carburetor’s supply is disrupted, and the carburetor fails to prepare the right fuel-air mixture. When the fuel-air mixture with wrong ratios is fed to the combustion chamber, its combustion is improper and incomplete. This results in less power. Therefore, a small engine with a faulty fuel system will fail to run smoothly and efficiently. A defective fuel system can also cause other problems, such as not starting.

The most common fuel system components of a small engine include the fuel tank, fuel pump, fuel valve, fuel line, fuel filter, air cleaner, carburetor, and governor. The fuel system should be checked, serviced and cleaned regularly.

Before starting with any fix, ensure that the mower is turned off. Disconnect the spark plug cables to make sure that the engine can not start unintentionally. Use safety goggles to protect your eyes. In general, cleaning the fuel line is not a big job for users that are familiar with the fuel system. If you are less familiar, it is good to learn more about the fuel system first. This helps to find the location of the various components and how they are connected. Often you can find detailed information in the manufacturer’s manual.

Fuel Line:

A fuel line is a hose responsible for the supply of fuel from the tank to the carburetor. Fuel lines of small engines are usually made of synthetic rubbers such as neoprene. Fuel lines can become dirty and clogged over time, and when this happens, they must be either cleaned or replaced.

● Fuel line servicing:

To service a fuel line, the first step should be to turn off the fuel valve. If your lawnmower does not have a fuel valve, empty the gas tank. If your lawnmower has a fuel valve, it is often located near the gas tank base, at the location where the fuel line is attached to the fuel tank body.

Once this is done, disconnect the carburetor’s fuel line from the carburetor. Empty the fuel line and inspect it for hairline cracks or damage on its surface. If the fuel line is cracked or damaged, there is no point in trying to repair it. It would be best if you replaced it with a new one.

Use a flashlight to inspect the fuel line for any accumulation of dirt and debris in it. Dirt and debris can reach the fuel line because of dirty fuel or a dirty fuel tank. You can remove dirt from the fuel line by blowing air through it or using a thin wire to push it out. If you use a thin wire to clean the fuel line, be careful because it is easy to rupture it.

Gas sitting in the tank for an extended period of more than a month or longer can produce a sticky gum-like substance that can clog the fuel line and the carburetor. You can use a fuel cleaner to remove the substance. We will provide details on using a fuel system cleaner in a later section in this blog post.

For your fuel system’s health, never let gas sit in the tank when your store the mower. Remove it before storing your mower, or use a fuel stabilizer.

Fuel Filter:

The fuel filters clean the gas before it goes to the carburetor. There are different types of fuel filters, depending on the brand and model. Some lawnmowers use a fuel filter at the bottom of the fuel tank, while others use a fuel filter that is present somewhere along the fuel line’s length. Some lawnmowers even use disposable in-line fuel filters that are made of folded paper.

Just like a dirty fuel line, a dirty fuel filter can also disrupt fuel flow. Cleaning fuel filters is usually not very easy, and the best approach is to replace them.

● Fuel filter servicing:

-Fuel filter located at the fuel tank bottom:

The first step to clean a fuel filter located at the bottom of a fuel tank is to close the fuel valve. Then take off the sediment bowl by loosening and removing its retainer nut. Empty the sediment bowl and clean it. Then clean the filter screen.

Once cleaned, fill the sediment bowl with fresh fuel and install it back, tightening the bowl retainer’s lock nut.

-In-line fuel filter:

An in-line fuel filter usually cannot be cleaned and must be replaced for undisrupted fuel flow. To replace an in-line fuel filter, shut off the fuel valve, or clamp the fuel line to block flow. With this done, remove the fuel filter from the fuel line, and install the new one. The new in-line fuel filter should exactly match the one being replaced. Once the new filter is installed, turn on the fuel valve, or unclamp the fuel line.

Fuel Tank:

A clean fuel tank is crucial for an unclogged fuel system. A fuel tank may be pressurized or unpressurized depending on whether the mower has an onboard fuel tank or a fuel pump, respectively.

● Gas tank servicing:

To service your gas tank, the first thing to do is ensure that there is no vapor lock. The fuel tank’s gas cap has a small hole in it to escape hot gases and entry of fresh air. If this hole gets clogged, it will result in a situation that causes a vapor lock. Vapor lock can prevent gas flow from the tank to the fuel line and cause the fuel to flow back from the carburetor into the fuel line. So, take off the gas cap and check if its hole is dirty. If it is dirty, clean it.

The next step is to drain the gas out of the tank. You can do this by disconnecting the carburetor’s fuel line and allowing gas to drain through it into a bottle or a pan. Once the tank is empty, use a flashlight to examine its bottom surface for a buildup of sediments and debris. Clean the tank thoroughly with soap and a slim brush and allow it to dry before refilling it.

If the gas tank is cracked, it must be replaced.

Using a Fuel System Cleaner:

Gas sitting in the tank for a prolonged time can cause a gummy buildup at various locations in the fuel system. Depending on the gas type, this can already start from a month. The best way to remove this gummy material is by using a fuel system cleaner. Make sure you use a cleaner suited to your lawnmower. In this regard, consult the manufacturer.

Using a fuel cleaner is to fill up the tank with a gallon of fresh fuel and add two tablespoons of cleaner to it. Start your mower normally, and run it with a normal throttle. Use the mower until the added gallon of fuel is used. Then fill your tank with fresh gas for later usage.

We recommend adding a fuel system cleaner to your mower’s gas tank once every 30 to 60 days to keep the fuel system clean.

Final Remarks:

A small engine’s fuel system is an essential part of your gas lawnmower. A clean fuel system is necessary to deliver an undisrupted supply of fuel to the combustion chamber. Keeping the fuel system clean and clear requires regular maintenance, which is not too difficult and can easily be performed by the user. In addition to regular maintenance, using a fuel system cleaner can also ensure a clean fuel system. 

Recent Posts