Fuel Injection System - Diesel: Operation: Governor

The governor controls idle and maximum RPM. Internal design enables the governor to have no effect on pump operation during normal operating speed range, when the accelerator is directly connected to the injection pump fuel rack. The altitude compensator does modify injection slightly during this range, compensating for air pressure variations with altitude.

Through governor action, engine RPM is held constant at idle speed, regardless of engine operating conditions (cold engine, air conditioner operation, power steering, or automatic transmission). At 5000-5100 RPM, governor limits RPM by pulling main rack back, until balance exists between engine RPM and fuel delivery.