Discover the Cause of Your Lawnmower’s “Low Gas” Symptoms!

As you continue to mow, your lawn mower start to sputter and stall. You worry that it isn’t getting fuel, but when you check the tank, you find that it is actually full. So, what’s the deal here?

If the fuel filter, the fuel line, the fuel system, the carburetor, the gas cap, the presence of water in the fuel tank, or the age of the gas are all clogged, the lawnmower may appear to be out of gas.

Always operate in a well-ventilated environment when servicing your gasoline system. Follow all the safety precautions advised in the mower’s instructions.

Lawn Mower
Lawn Mower

Before diagnosing, repairing, or operating, make sure you’ve read and understood all of the safety instructions in the equipment’s operator’s manual. If you lack the knowledge, experience, or physical ability to complete the repair safely, you should seek the advice of a professional.

Here Are 7 Causes Your Lawnmower May Be Low on Gas

Your Lawnmower’s Fuel Is Old or Bad

If your lawn mower is acting like it’s out of gas, investigate the quality and freshness of the fuel first. Ethanol is now a common additive to gasoline.

Fuel derived from corn or other high-starch plants is being developed as a cleaner alternative to traditional gasoline. While ethanol has environmental benefits, it should be avoided in small engines like the one on your lawnmower.

The ethanol in the fuel will draw water from the air. When put into a lawnmower’s fuel system, this ethanol and water mixture will cause premature corrosion of parts and leave behind a varnish that gums up the fuel system, making the mower act as if it were out of gas.

Gasoline can start to degrade as soon as 30 days after purchase, so it’s best to use it up as soon as possible.

Use a fuel stabilizer like Sea Foam Motor Treatment if you have more gas than you can use within 30 days.

Sea Foam provides additional protection for the fuel system and helps keep moisture levels down, so I always make sure to add some to each tank I fill.

SOLUTION: Use a fuel siphon to transfer all of the gas from your tank to a safe container. Put in new gas that has a fuel additive like Sea Foam to clean the fuel and dry it out.

Find out why adding Sea Foam to your fuel is a good idea.

Your Lawnmower’s Fuel Filter Is Blocked

To prevent dirt and other contaminants from entering the fuel system, the fuel filter strains fuel as it exits the fuel tank. Due to clogging, the fuel flow through this filter is reduced.

You may be experiencing the symptoms of a low gas tank because your lawn mower is not properly fueled.

Filters should be changed at least once a year and more frequently if dirty gas is detected.

SOLUTION: Changing the gasoline filter should solve the issue. Make that the indicator on the filter housing is facing in the direction of gasoline flow before you install it. This means that rather than pointing at the fuel tank, the arrow should be directed at the carburetor.

Obstructed Gas Flow in Your Lawnmower

As fuel ages, it can leave behind gummy deposits in the fuel lines. In the presence of these deposits, the fuel line’s orifice is reduced in size, reducing the fuel’s ability to flow freely.

In order to determine where a blockage is located in a fuel line, it is necessary to examine the entire line.

The solution is to open and close the fuel shut-off valve at the fuel tank’s base. The absence of a fuel shut-off valve is not cause for alarm. There are mowers out there without one.

If your lawnmower doesn’t have a fuel shut-off valve, you can crimp the fuel lines with hose pinch pliers.

Locate the blockage in the fuel line and clear it:

  • Take the fuel line apart and work on it one section at a time. If the line is flowing normally the farthest away from the tank, there is no need to inspect any other parts of the line.
  • You can use the fuel shut-off valve or pinch pliers to halt the fuel flow.
  • Take out the fuel line’s end that is farthest from the tank and set it aside. If you want the fuel to drain away from the tank, set the container lower than the tank.
  • Turn on the gas again.
  • If fuel is not flowing freely into the storage tank, the restriction in the fuel line must be fixed. To do this, disconnect the fuel line from your mower and shut off the fuel valve.
  • Use carburetor cleaner sprayed into the hose and compressed air to clear the line. Keep trying until the fuel line is free of obstructions.
  • Replace the mower’s gas line.
  • If the fuel line cannot be cleared to allow unrestricted fuel flow, a new fuel line must be installed. If the fuel line is dry and has cracks, you should replace it before it leaks.

Lawnmower’s Fuel Pump Is Bad

Only if the fuel tank is lower than the carburetor will your lawn mower have a plastic or metal fuel pump.

By drawing pressure from the engine’s crankcase, a vacuum fuel pump creates a vacuum in the fuel tank. The fuel is forced upward into the carburetor by this pressure.

Fuel pumps need to be replaced when they develop cracks, become damaged, or begin leaking.

SOLUTION: If the fuel pump is not visibly broken or leaking, it is time to perform some diagnostics to make sure it is functioning properly.

Verify fuel flow to the pump to ensure it is getting fuel and is therefore functioning. It’s possible that you looked for blockages in the fuel lines in the previous step, in which case you can skip this one.

Remove the fuel line from the carburetor and set it aside once you’ve established that the fuel pump is receiving an adequate supply of fuel.

Following this, you should turn on the gas and start the mower. If your fuel pump is functioning properly, you should see fuel dripping or pulsating out of the fuel line.

If the fuel pump is damaged or broken and is no longer releasing fuel, you should have it replaced.

Your Lawnmower’s Carburetor Is Filthy.

The carburetor controls how much air and fuel are mixed together and injected into the cylinder. The carburetor on your engine is attached to the top or side of the block. It’s typically situated either beneath or behind the air filter.

If your carburetor is dirty, its parts, including the fuel jet, could clog or get stuck, cutting off fuel to your mower’s engine.

SOLUTION: The problem can be fixed by removing the air filter and spraying carburetor cleaner into the intake. Considering that starter fluid is a dry chemical, I find that cleaning the carburetor is more effective.

Get the car going to see if it still runs. Your lawn mower’s carburetor probably needs cleaning if it fires up and runs smoothly for a while, but then loses power, as if it weren’t getting fuel.

Defected Gas Cap on Lawnmower

Pressure inside the fuel tank must be equal to atmospheric pressure outside the tank, which requires adequate venting. By creating a vacuum inside the tank, blocking the vent causes the mower to run out of gas.

In most models, the fuel cap also serves as the mower’s vent. The fuel tank can breathe thanks to the cap.

SOLUTION: If you suspect a faulty fuel cap, try operating the mower both with and without the cap.

If your mower starts and runs smoothly when you remove the fuel cap, but sputters and acts like it’s not getting fuel after you replace the cap and let the mower run for a while, the fuel cap may be broken.

Fuel Tank Contamination

Water in the fuel tank can make a lawnmower act like it isn’t getting gas if you leave it out in the rain or if you store it for a long time. There can be no combustion in the presence of water.

Due to the density difference between water and gas, the water will always settle to the bottom of the fuel tank. The use of a flashlight could allow you to locate water.

SOLUTION: After finding water in the gas tank, the obvious solution is to drain the tank. Remove the bowl from the carburetor and drain the fuel from the fuel lines.

After water has been drained from the fuel lines and tank, it can be removed with air. In order to keep my mower running smoothly, I always use new gas that has a fuel additive like Sea Foam added to it.

When you combine this gas with the Sea Foam, you can refill the tank. Turn on the mower and let it run for a while so that the new gas and stabilizer can be pumped through it.


Using the correct fuel in your lawn mower and replacing the fuel on a regular basis will reduce the amount of buildup and wear on the fuel system.

You should inspect the fuel filter, lines, pump, and carburetor if your lawnmower is not getting gas.