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.
What causes a lawn mower to idle up and down?
Carburetor Adjustment
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. One screw controls the idle speed while the other adjusts the idle mixture.
Why is my lawn mower pulsing?
Problems in the Fuel System
Check and clean the vent. Surging is also caused by water that got into the fuel. A mower left in a heavy rain or condensation on a hot summer day can choke the engine. Empty the gas tank, properly dispose of the old fuel and try a fresh batch of gasoline.
How do I adjust the throttle on my Briggs and Stratton?
How to Adjust a Briggs & Stratton Throttle Link
Remove the screws that hold the air cleaner in place with a Phillips-head screwdriver. Inspect the engine to locate the choke lever, also known as the choke arm. Adjust the throttle lever to the “Fast” or “High” setting.
What does the governor do on a Briggs and Stratton engine?
The governor system is like a cruise control system. It maintains the speed of your lawn mower or outdoor power products. When Briggs & Stratton governors are adjusted properly, they keep your speed steady regardless of engine load – the amount of work the engine must perform.
How do small engine governors work?
How Mechanical Governors Work. A mechanical governor uses flyweights to create a force based off of crankshaft speed which is balanced by the force of the governor spring. The top engine speed is varied by increasing the spring force to run faster or decreasing the force to run slower.
