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 small engine to surge up and down?
A dirty or gummed up carburetor causes an engine to surge. … Serious problems — such as damaged gaskets, broken jets or internal parts that will not come clean — require the installation of a carburetor kit or a carburetor replacement.
Why is my push mower revving up and down?
Airflow Issues. 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 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.
How do you troubleshoot a Briggs and Stratton engine?
Your Mower Won’t Start:
- Loose, Dirty or Disconnected Spark Plug in Your Lawn Mower: Check it out, clean off debris, re-connect and tighten.
- Dirty Air Filter: Clean or replace.
- Fuel Not Reaching the Engine: Tap the side of the carburetor to help the flow of gas. If this doesn’t work, you might need a new fuel filter.
What causes an engine to 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.
Why does my lawn mower rattle?
One of the more serious noises is a rattling sound, as this can signify that you have loose parts that might come dislodged. The minute you hear rattling, it is imperative that you tighten the blade, flywheel, and other parts.
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.
Is the governor spring is the only force on the throttle shaft when the engine is not running?
The governor spring is the only force on the throttle shaft when the engine is not running. … If the flywheel key shears on an engine equipped with a Magnetron ignition armature, the armature will continue to create energy and a spark at the plug but at the wrong time.