Question 57Motor Plants - Assistant Engineer

The correct answer is C) rack position. The amount of fuel delivered by a unit injector is controlled by the rack position, which regulates the fuel flow. The rack is a mechanical component that moves in response to the engine throttle, adjusting the fuel supply to the injectors and controlling the engine's power output. The other options are incorrect because: A) the camshaft controls the timing of the fuel injection, not the amount; B) the main spring is not involved in regulating the fuel delivery; and D) the engine speed is a result of the fuel delivery, not a controlling factor.