What causes a lawnmower engine to surge?
Problems in the Fuel System
The cap on your mower’s gas tank is vented with a small hole. … 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.
Why is my lawn mower revving up and down?
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. … Then slowly adjust the screws tighter or looser in turn until the mower runs and idles smoothly.
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.
Why is my lawnmower 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.
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.
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 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 does my push mower idle low?
A lawn mower’s engine continues to run at low speeds when idling, pulling just enough fuel and air into the carburetor to keep combustion going. If the mower doesn’t idle properly, it’s usually because of a loss of fuel or air in the carburetor at these low speeds.
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.