Generator starts then quickly shuts down with 'Overspeed' alarm; engine sounds like it is racing before shutdown.

Safety: Do not repeatedly start an overspeeding engine; severe mechanical damage can occur. Turn the controller to OFF and disable automatic operation.

• Inspect throttle and governor linkage: With the engine off, move the throttle plate by hand to ensure it moves freely. Check the governor arm and linkage for binding, corrosion, or disconnected springs. Lubricate pivot points and reattach any loose linkage.
• Check electronic governor actuator: On models with an electronic actuator, inspect the actuator rod and wiring harness. If the actuator is stuck in an open-throttle position or does not respond to control signals, replace the governor actuator.
• Inspect engine speed sensor: Locate the magnetic pickup or Hall-effect speed sensor near the flywheel. Check for metal debris on the sensor tip and clean it. Verify proper air gap per Generac specifications. Replace the sensor if damaged.
• Controller calibration: If mechanical parts are fine, the control board may be misreading speed. A Generac technician may need to recalibrate or replace the controller.