Lawn Mower Starts, then Dies.

Last Modified

March 13, 2023 by Hirah Ehsan

When your mower starts up, you’re ready to attack the towering green blades, only to have it fizzle out. When your lawnmower doesn’t start, you want to know what’s wrong and how to repair it. To help you fix your mower, I’ll go through the five most prevalent reasons for this issue and what you can do about each one when your lawnmower starts then dies.

If your lawnmower doesn’t start, you’re not alone. However, this issue is more frequent than you may imagine, and the solution is relatively straightforward.


Carburetor clogging is a possibility. Leaving gasoline in the lawnmower for an extended time is the most typical cause of a clogged carburetor. An increase in the thickness and stickiness of the fuel is possible due to the evaporation of some of the constituents. The carburetor might become clogged up, and the engine will stall if you use this sticky gasoline. You may use carburetor cleaner to clear a blocked one. The carburetor should be rebuilt or replaced if cleaning is ineffective.


The fuel tank’s level decreases as the engine uses gasoline. The gasoline cap has a tiny vent to let air into the tank to compensate for this. A “vapor lock” will develop if the gasoline cap vent becomes blocked, preventing air from entering the tankā€”the engine stalls due to a lack of gasoline to the carburetor. A clogged fuel cap vent may determine by squeezing the cap slightly and then running the engine. If the engine continues to run after removing the gasoline cap, the fuel filter has to be changed since it is likely blocked.

An out-of-date spark plug.

The spark plug ignites the gasoline mixture in the engine chamber. The lawnmower engine will either not ignite or die fast if the spark plug is filthy or worn out. The carbon or dirt may be removed using a scrub brush and a cleaning liquid.

Because of the carbon accumulation on its tip, a sufficient spark cannot generate in the ignition chamber. You can replace the starter motor and clean the end of the ignition system wire of any combustion byproducts or oil residues. Also, look for any evidence of wear or fractures on the surface.

You may remove the lawnmower’s spark plug and connect it to the engine’s intake and attempt to start it. Sparks should be seen from the end near the twisted electrode and lower pin. If the flash isn’t visible, it’s time to get a new one. In addition, a faulty spark affects the engine’s fuel economy. Your lawnmower will need extra fill-ups as a result. White smoke is produced due to a lack of ignition whenever the fuel is injected.

Trouble starting the engine is another indicator of a damaged spark plug. If the mower can create, it rapidly dies once the throttle is pushed. As the spark plug wears out, it becomes harder to maintain a higher engine speed with fewer sparks.

Wrecked Gasoline (Formed Residues)

As soon as 30 days have passed since you last used the gas in your lawnmower, the volatile components have evaporated and left behind a thick oily residue. The gas line and other elements that limit gas flow will get clogged with this residue, and your lawnmower will no longer operate.

You may also run the engine to purge the carburetor of as much gas as possible by completely draining the gas tank. Fuel stabilizer and new gas should be added after the tank is empty. It’s a good idea to have a fuel stabilizer on hand, but it won’t help the engine withstand the ravages of time.

A fuel stabilizer is a low-cost item that will extend the life of your lawnmower. Make careful to follow the instructions in your mower’s owner’s handbook to ensure that the gasoline-to-stabilizer ratio is correct. You may add additional gas to the old fuel to dilute the waste, but we prefer to use fresh gas.

The Reservoir is overflowing with oil.

Check and clean the carburetor, petrol tank, and spark plug, but if your lawnmower continues to die, it may be because the oil reservoir is too full. Smoke pouring from the engine is a telltale indicator that something is wrong. Eventually, the engine will shut down because it takes in too much oil.

Alternatively, tilt the lawnmower for a period to allow the oil to spread throughout the machine. Allow the engine to cool down before starting it up again. If it doesn’t stall for an extended period, you know that the problem is excessive oil. It’s a simple repair once you figure it out, and you’ll need to empty the oil. A siphon may use, or you can flip the mower over and let the oil drain out of the opening.

Using a dipstick to monitor the fuel level and remove or add till you get to the desired level. The mower should be reinstalled, and the mower should start again. There should be no smoke, and the mower should normally function when you remove the smoke. As a general rule, people tend to overfill their oil tanks, and they prefer to do it themselves. However, if you discover it early enough, there is no reason to be alarmed.

Why does my lawnmower only run for a few seconds then die?

The most typical causes of a lawnmower that starts to run briefly and then dies are a block carburetor bowl or a dirty carburetor. Spark plugs that are dirty or faulty.

Why does my lawnmower start but not stay running?

Checking the fuel tank and oil storage for fullness is the first step in diagnosing a lawnmower that won’t start. However, the issue might also be an inappropriate blend of gas and oil or even a filthy spark plug. Even so, you may require a lawnmower repairer to get you up and running again.

What’s wrong with my mower?

A blocked air filter is the most typical reason for a lawnmower malfunctioning. Check whether the air filter is blocked with oil and dirt by removing the lid from the compartment. Buy a new paper filter if it is filthy.

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