The most common reason for a surging lawn mower engine is a blockage in the fuel supply , but there are other possibilities: Bad gas. Bad spark plug. Dirty / faulty carburetor.
Why is my lawn mower not running smoothly?
A dirty air filter is one of the most common causes of a poorly running lawn mower, since it starves the engine of the oxygen needed for combustion. Fuel Filter: Check the fuel filter on the mower to make sure it's clean, and replace it if needed.
What causes a riding lawn mower to sputter?
Dirty air filters are one of the most common reasons lawn mowers sputter. Dirt can be present in the apertures that lead from the carburetor and the fuel filter and interrupt the flow of fuel supply to the combustion chamber.
What causes a riding lawn mower to idle up and down?
A carburetor that's incorrectly adjusted is a common cause of poor engine idling that results in hunting and surging. Fortunately, most lawnmowers have two screws that allow you to adjust the carburetor yourself. ... Then slowly adjust the screws tighter or looser in turn until the mower runs and idles smoothly.
What are the symptoms of a bad coil on a riding lawn mower?
One of the symptoms of a bad lawn mower ignition coil appears when you are mowing the lawn and the mower gets hot and literally shuts off . The mower must cool down over a period of time and will start and run for awhile until it gets hot again, at which time it will shut off again.
Will a bad spark plug make a lawn mower run rough?
Replace a lawn mower spark plug
The spark plug gets electrical current from the ignition coils and sparks to ignite the fuel mixture in the cylinder, which drives the piston. ... The engine won't start or runs rough if the spark plug is bad . Replace the spark plug if it's damaged or coated with residue.
How do I know if my lawn mower carburetor is bad?
- The lawn mower engine has trouble starting.
- The engine starts but stalls while you're cutting the lawn.
- The engine runs rough during mowing.
- Black smoke is seen coming out of the muffler.
- There is a noticeable increase in fuel consumption during normal lawn mower use.
How do you adjust the idle on a lawn mower?
Tighten the idle adjustment screw, found on the side of the carburetor, by turning it clockwise just to the point where you feel it lightly touching the seat of the carburetor. Back the screw off (turn counterclockwise) from this point one-and-a-half turns.
What causes a carbureted engine to surge?
Incorrect fuel mixture adjustments and engine idling capabilities can be upset by fuel mixture adjustments and fuel vapor recovery system malfunction. The fuel system cleaner added to the fuel tank can open blocked passages in the fuel system that could be causing the surge.
What are signs of a bad ignition coil?
- Engine misfires.
- Rough idle.
- A decrease in car power, especially in acceleration.
- Poor fuel economy.
- Difficulty starting the engine.
- Check engine light is on.
- Exhaust backfiring.
- Increased hydrocarbon emissions.
How do you test a coil on a riding lawn mower?
- Step 1: Remove the ignition coil from the lawnmower.
- Step 2: Test the ignition coil using a multimeter.
- Step 3: Purchase a new ignition coil if the test fails.
- Step 4: Install the new coil.
- Step 5: Test the lawnmower with the new ignition coil.
Why does my lawn mower sound like it's turning off?
When a lawn mower surges, it sounds as if the engine reaches full speed, only to decelerate quickly . Typically, it doesn't die, but the surging may repeat during the entire time the mower is in use. Like other small engines, mowers rely on a precise volume of gasoline and air for smooth operations.
How do you clean a carburetor on a lawn mower without taking it off?
However, you can not spray the carburetor when the engine is off since it cannot do the cleaning without being propelled. All you need to do is to start the engine and spray directly at the center of the carburetor while it is running. Any deposits clogging in the carburetor will easily be removed.
Why does my mower run rough?
The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the lawn mower for a long period of time. ... This sticky fuel can clog up the carburetor and cause the engine to run roughly. If the carburetor is clogged, try cleaning it with carburetor cleaner.
