Why does my lawn mower keep revving?

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.

How do I stop my lawn mower from surging?

Inspect the vent on your gas tank’s cap and clean it if it’s dirty. Drain the gas tank, clean the gas bowl, and add a fresh batch of fuel. Or you can inject fuel cleaner to clean the fuel line. After changing the fuel or injecting fuel cleaner run the lawn mower as usual.

Why does my lawn mower pulsate?

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.

Why is my mower surging?

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.

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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.

How do you adjust the idle on a lawn mower?

How do you adjust the idle on a lawn mower?

  1. Loosen the set screw in the center of the air filter with a flathead screwdriver.
  2. 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.

Can spark plugs cause 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.

How do I clean the carburetor on my lawn mower?

Step-by-step guide to cleaning lawn mower carburetor

  1. Safety first. …
  2. Check to see if the problem really is the carburetor. …
  3. Remove the outer casing and air filter. …
  4. Unbolt the carburetor and remove it from the fuel line. …
  5. Unbolt the bowl and clean the nut. …
  6. Replace the needle.

How do you fix a surging idle?

Turn the engine off again, and reattach the air intake duct work to the throttle body. Start the engine and rev and hold to 1,500 to 2,000 rpm until no white smoke is coming out of the exhaust pipe. Cleaning the Idle Air Speed Control Valve with aerosol throttle cleaner can often solve an idle problem.

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How do you adjust a carburetor on a lawn mower?

Set the throttle to fast and start the mower engine. Turn the high speed screw first clockwise until the engine slows, then counterclockwise until it slows. Locate the center point where the engine idles best. Move the throttle from slow to fast then back to slow to test the adjustment.

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