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.
What causes a small engine to rev 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.
What can cause surging on a Briggs and Stratton motor?
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 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 fix a surging idle?
The cure for this condition is to clean the valve with some aerosol throttle cleaner or engine top cleaner. Here’s how to clean the IAC valve: Disconnect the air intake ductwork from the throttle body. Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm.
How do you adjust the governor on a small engine?
To adjust the governor, you would loosen the screw on the bottom of the governor arm and push the governor arm so the throttle is wide open. Then you would turn the bottom “clip” (which is connected to the governor shaft) counter clockwise. This will set the governor shaft on top of the governor spool.
How do I fix my Kohler engine surging?
You may have already done these but may be worth mentioning; Make sure the gas tank cap vent is working ( take the cap off and see if the surging stops). Check the air filter. Check/replace the fuel filter. Drain old gas, make sure there isn’t any water that may be present in the tank left behind.
Can spark plugs cause surging?
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 you adjust the idle speed on a Briggs and Stratton engine?
How to Adjust the Idle on a Briggs & Stratton Lawn Mower
- Loosen the set screw in the center of the air filter with a flathead screwdriver. …
- 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.
Why does my lawn mower only run for a few seconds then dies?
If your lawn mower starts, runs briefly, then dies these are the four most common reasons that’s happening: Dirty carburetor / clogged carburetor bowl. Old gasoline that has gone bad. Dirty or defective spark plugs.
What does surging mean?
To rise and move in a billowing or swelling manner. 2. To roll or be tossed about on waves, as a boat. 3. To move like advancing waves: The fans surged forward to see the movie star.
What causes RPM to fluctuate while idling?
Why does my engine’s RPM seem to fluctuate (runs rough)?
Engine hunting and surging at idle is usually caused by a fuel delivery, air leak, or governor system problem. Cleaning/overhauling the carburettor, adjustment of the governor, and/or changing the air filer may be required.
What causes RPM surge?
For the engine surging making the rpm’s go up and down could be caused by a defective or stuck idle air control valve (IAC). … To calibrate the throttle pedal position sensor, turn on the key with the engine off and push the gas pedal to the floor slowly. Hold the pedal on the floor and turn off the key.
What can cause erratic idle?
Erratic engine idle can be caused by various factors, but the most common and likely cause is a dirty or malfunctioning Mass Air Flow (MAF) sensor. This is a device found in fuel-injected cars and measures air flow so that the appropriate amount of fuel can be injected.
What does engine surging feel like?
You may notice the tachometer fluctuating, for example, from 1500 to 2000 rpm. At the same time, you may feel a soft and rhythmic jerking motion. The problem may come from a faulty sensor or system that is making the computer deliver too much or too little fuel, and then try to correct the fault by over-compensating.
Can a bad fuel filter cause surging?
A badly clogged fuel filter will reduce fuel pressure enough that the ECM must open the fuel injectors more to maintain the same amount of flow. … Fuel injectors contain very fine mesh filters, which can just as easily clog and cause the same sort of surging.