Red Seal Heavy Duty Equipment Technician Practice Exam

What primary function do injectors serve in a diesel engine system?

1. To regulate exhaust flow

2. To atomize fuel for combustion

3. To supply air for combustion

4. To cool the engine components

The correct answer is: To atomize fuel for combustion

In a diesel engine system, the primary function of injectors is to atomize fuel for combustion. When the injector sprays diesel fuel into the combustion chamber, it breaks the fuel into fine droplets, allowing for a better air-fuel mixture. This atomization is crucial because it enhances the efficiency of combustion, ensuring that the fuel burns more completely and effectively, leading to improved power output and reduced emissions. Each injector is calibrated to deliver a specific amount of fuel at the right pressure and timing, significantly influencing the engine’s performance. When fuel is atomized properly, it can ignite more readily when compressed by the piston, leading to the desired combustion process. Other functions such as regulating exhaust flow, supplying air for combustion, and cooling engine components are important in the overall operation of a diesel engine but do not pertain to the injectors specifically. Instead, these roles involve different systems within the engine, such as the exhaust system for exhaust flow regulation, the intake system for air supply, and the coolant system for temperature management. Thus, the key role of injectors revolves solely around fuel atomization necessary for optimal combustion.