The governor in a diesel engine primarily controls which of the following?

The governor in a diesel engine primarily controls the fuel entering the cylinders. Its main function is to maintain the engine speed by adjusting the amount of fuel injected into the combustion chamber. When the engine speed increases, the governor reduces the fuel supply to prevent overspeeding. Conversely, when the engine speed decreases, it increases the fuel supply to regain the desired speed.

By regulating the fuel flow, the governor plays a crucial role in optimizing engine performance, efficiency, and stability during operation. This is particularly important in diesel engines, where fuel management is essential for both power output and emissions control. The precise control of fuel injection directly impacts the combustion process, making the governor a vital component for the engine's operation.