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A lawnmower that hunts and surges may be experiencing something as simple as an airflow issue. If the air that the engine requires to run is blocked, especially sporadically, it can cause the engine to slow down. When the blockage moves or clears, the engine may suddenly rev up in response.
Why does my lawn mower sound like it is surging?
When a lawn mower surges, it sounds as if the engine reaches full speed, only to decelerate quickly. Like other small engines, mowers rely on a precise volume of gasoline and air for smooth operations. If either of these is exceedingly rich or lean, surging may result.
What causes an engine to hunt and surge?
If an engine is not getting enough fuel (this is called “running lean”), due to fuel pressure (regulated by the fuel pump and regulator), restricted fuel injectors, a vacuum leak or really anything that throws off the fuel mixture going in to the engine, this can cause the surge.
What does engine surging mean?
Engine surging is when an engine starts easily and accelerates smoothly, however after a few minutes at a steady speed, it either surges in speed or misfires. Misfiring happens when one of the cylinders of an engine’s combustion cycle fails.
Why is my lawn mower chugging?
Clogged or Dirty Air Filters 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. You want to be sure to clean or replace dirty air filters.
How do you fix a surging idle?
Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm. Turn the engine off to allow the cleaner to soak into the IAC passageway. Restart the engine, rev and hold at 1,000 to 1,500 rpm, and repeat the cleaning process again.
Where is the air filter on a lawn mower?
A lawn mower’s air filter is usually located near the top of the engine and is encased within a metal or plastic shroud that is usually secured by a screw or with snap fittings.
What can cause surging on a Briggs and Stratton motor?
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 does the RPM go up and down?
RPM fluctuation is a common symptom of worn-out spark plugs, especially in older vehicles. Spark plugs that are worn out are unable to correctly fire the fuel within the piston at the appropriate time. This might result in sluggish acceleration. When accelerating, your automobile may experience misfires and jerking.
What causes engine to idle up and down?
Causes of a rough idle. Many different problems could result in a rough idle for your car or truck, including: dirty fuel injectors, clogged air filters, bad spark plugs, and a variety of exhaust system issues.
What would cause the idle to go up and down?
Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor.
Can bad spark plugs cause engine surging?
3. Surging and Lagging. Another good indication that your spark plugs are dirty or worn is if your vehicle experiences surges of speed, resulting in a jerking acceleration. These surges occur because your spark plugs are not igniting the fuel in your engine at the proper rate, resulting in an uneven speed.
Can a dirty fuel filter cause engine surging?
Poor Engine Performance Under heavy loads, a clogged fuel filter may cause the engine to randomly hesitate, surge or sputter. Although there may be no symptoms under normal driving conditions, a clogged fuel filter will starve the engine of the extra fuel needed when quickly accelerating.
What are the symptoms of a bad spark plug?
What are the signs your Spark Plugs are failing? Engine has a rough idle. If your Spark Plugs are failing your engine will sound rough and jittery when running at idle. Trouble starting. Car won’t start and you’re late for work… Flat battery? Engine misfiring. Engine surging. High fuel consumption. Lack of acceleration.
How do I stop my lawn mower from sputtering?
A Mower Has to Breathe A dirty air filter inhibits the flow of air into the carburetor. Clean or replace the air filter to stop the mower from sputtering to a halt. Too much air can also cause problems for the engine.
How do you fix a lawn mower sputter?
Remove the cap of the gas tank and look in at the gas. Inspect the gas for signs of water. Turn the mower over so the oil case is sitting under the carburetor. Set a drain pan under the oil plug. Check the underside of the unit for caked on grass. Excessive grass under the deck will make the mower sputter.
Why is my lawn mower not running smoothly?
Causes: If the engine starts, but does not run smoothly, it means that the spark plug and ignition system are in order and you need to look elsewhere for the source of the problem. The usual culprit is air intake or fuel system related.
Why is my engine revving in park?
The idle is controlled by the idle air control valve and if it cannot keep the engine idling it will keep trying to rev the engine up to compensate. A vacuum leak, sensor that has failed, or an EGR system malfunction could potentially be the cause of the erratic engine you’re experiencing.
