Reviewed for compliance by small engine technician
Your lawn mower may surge a little bit sometimes when you start it, then the surge goes away. There’s nothing to worry about that.
However, if it keeps surging while you’re using it like going up and down or even dies, then you have every reason to be concerned. Although it may mow your lawn competently, the whole time you’ll probably be thinking, “why does my lawn mower sound like it is surging?” It won’t be such an enjoyable mowing session, will it?
Lack of enough supply of fuel to the engine is the usual reason behind surging. But there are also other possibilities so let’s look at the possible causes of the fuel starvation along with how you can fix them yourself.
Note: This guide would generally apply to all gas lawn mower brands such as Honda, Greenworks, Craftsman, PowerSmart, Yard Machines, Briggs & Stratton, Toro, Lawn-Boy, Columbia, Jonsered, Poulan Pro, Kawasaki, Troy Bilt and many others.
Clogged Air Filter
The air filter is the first thing you’ll want to check when looking to fix your surging mower. If it’s dirty, it starves the mower engine of the oxygen required for combustion.
Is the engine still surging after fitting the new or cleaned air filter? Read on to get more troubleshooting tips.
This the most common cause of surging issues. Grime and dirt can gum up the internal components of your carburetor, making it fail to receive the correct flow of fuel.
Fuel System Problems
The fuel tank cap has a small hole, which allows air to flow into the tank and create back-pressure to help deliver fuel to the carburetor. Dust or dirt can plug up this hole. As a result, the carburetor won’t get enough fuel, leading to surging.
Surging can also occur due to water contaminating your fuel. Water can enter gasoline through condensation on a scorching summer day or heavy rain.
If your carburetor is loose, it will suck air in through the crevices between it and the engine block. The excess air will unbalance the gas to air ratio.
The imbalance will compromise the vacuum required to move fuel and air properly through the carburetor at the recommended rate, resulting in irregular engine performance.
If you still have problems with your mower after performing these fixes, it may have serious engine problems that need professional repair.
Remember, performing mower maintenance at the beginning of each mowing season will significantly help protect it from problems.