Best answer: What causes a lawn mower to idle up and down?

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.

What causes an engine to rev up and down?

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 causes a lawn mower to run sluggish?

Maintenance lapses become evident when the mower turns over slowly or begins to falter at start-up. The fault could be a dirty spark plug, air filter or carburetor, or it could be related to the quality of the gasoline used. Slow starting can also be the result of a failure to clean the blades.

IT IS INTERESTING:  Quick Answer: Is a manual lawn mower good?

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?

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.

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.

What causes RPM to fluctuate while idling?

Why does my engine’s RPM seem to fluctuate (runs rough)?



Many engine performance problems can be linked to maintenance issues such as stale fuel, dirty air filter, fouled spark plug, and deteriorated oil. … Engine hunting and surging at idle is usually caused by a fuel delivery, air leak, or governor system problem.

IT IS INTERESTING:  Best answer: What does Tym tractor stand for?

Why is my mower idling low?

When the mower has trouble idling, or idles too low, the mower will shut off. … Often this is caused by a decrease in air or fuel to the carburetor.

Why is my mower weak?

The primary reason your push mower may lose power is often dirt. There are two major locations to check out – the air cleaner elements, and the fuel system. … The second possibility is dirt and water in the fuel system. This will cause build-up in the carburetor, inefficient combustion, sputtering, and power loss.

Why does my lawn mower sound like it’s turning off?

Could be something as simple as the carb mount bolts working themselves loose which could just mean they need tightened or if it was ran this way mowing, some grass/dust/debris/etc could have made its way into the carb gasket and it needs cleaned off or just that gasket replaced… but might be easier in the long run …

Blog about special equipment