SPRING 6N6926 - Caterpillar

Probable Causes
Low trip point for engine overspeed
Binding of the actuator for the throttle
Energy of the driven equipment
Slow governor responseRecommended Repairs
The ECM immediately terminates the ignition when an overspeed occurs. Unburned gas remains in the air inlet and exhaust system.
Unburned gas in the air inlet and exhaust system may ignite when the engine is started. Personal injury and/or property damage may result.Before starting an engine that was stopped by terminating the ignition, purge the unburned gas from the air inlet and exhaust system. Refer to "Unburned Gas - Purge".
Check the Trip Point
Note: Do not program the trip point for engine overspeed higher than the maximum ratings of the driven equipment.The trip point or engine overspeed may be too low. Verify that the trip point for the engine overspeed is properly programmed. Typically, this parameter is set at 118 percent of rated speed.This parameter requires a factory password in order to change the trip point. Change the trip point to an acceptable speed.Check for Binding of the Actuator
Slide the electrohydraulic actuator's rod in and out while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.Check the Driven Equipment
Determine if the driven equipment has additional inputs of energy that could drive the engine beyond the rated rpm. Make corrections to the installation in order to prevent the overspeed from recurring.Check for Slow Governor Response
Observe the "Speed Governor Adjustment" screen on the Caterpillar Electronic Technician (ET). Look for the engine response to the worst cases for step-loading and unloading.Use "Throttle Bump" feature of Cat ET in order to disturb steady state engine operation. If the undershoot or the overshoot of the engine speed is excessive, refer to Troubleshooting, "Engine Misfires, Runs Rough Or Is Unstable ".