AG Mechanics CDE Practice Exam 2025 – Comprehensive Test Prep Resource

The spring in a governor system on an engine is designed to close the throttle valve. This is important for regulating the speed of the engine. When the engine runs at higher speeds than desired, the governor system uses the spring to close the throttle valve, reducing the amount of air and fuel entering the engine, thereby slowing down the engine. This action helps maintain a consistent and safe engine speed during different operating conditions.

The other options are incorrect:

- Opening the choke valve (Option B) is not the function of the spring in a governor system; the choke valve primarily controls the air-fuel mixture ratio during engine start-up.

- Pulling the throttle valve to the wide-open position (Option C) is not the primary purpose of the spring in a governor system; the spring is usually designed to provide resistance to throttle movement to control engine speed.

- Regulating fuel injection (Option D) is typically managed by the fuel injection system of an engine, not the spring in a governor system.