MDE 5 End of Unit Quiz

Answer: A) Scroll mechanism, camshaft, delivery valve, and pump housing
Explanation: The main components of a scroll type fuel pump include the scroll mechanism (which moves the fuel), the camshaft (which drives the scroll mechanism), the delivery valve (which controls fuel delivery), and the pump housing (which encloses the pump components). These parts work together to ensure efficient fuel delivery and operation.

Answer: A) Clogged nozzle orifices
Explanation: Clogged nozzle orifices can lead to poor atomization of the fuel, resulting in incomplete combustion, reduced engine performance, and increased exhaust smoke.

Answer: B) To prevent fuel leakage back into the pump after injection
Explanation: The delivery valve in Bosch or Jerk type fuel injection pumps prevents fuel from leaking back into the pump after it has been injected. It ensures that the injected fuel remains in the fuel lines and injector, maintaining proper pressure and volume for effective fuel delivery.

Answer: A) The nozzle tip
Explanation: The nozzle tip is responsible for controlling the spray pattern of the fuel. It ensures that the fuel is distributed in the correct manner to achieve optimal combustion.

Answer: A) Clogged nozzle orifices
Explanation: Clogged nozzle orifices can affect the performance of the fuel nozzle by disrupting the spray pattern and reducing the efficiency of fuel injection, which can lead to poor engine performance and increased emissions.

Answer: C) By modifying the position of the scroll or cam mechanism
Explanation: In scroll type fuel injection pumps, the delivered quantity of fuel is varied by modifying the position of the scroll or cam mechanism. This adjustment changes the volume of fuel that is pumped and delivered to the injector, allowing for control over the fuel quantity injected into the engine.

Answer: A) The depth to which fuel droplets penetrate into the combustion chamber
Explanation: In diesel engine fuel injection, "penetration" refers to the depth to which the fuel droplets travel into the combustion chamber. Effective penetration ensures that the fuel reaches the areas where it can mix thoroughly with air for optimal combustion.

Answer: A) Increased engine knocking and reduced power output
Explanation: Retarded fuel injection, where the fuel is injected later in the engine cycle, can lead to increased engine knocking and reduced power output. This is because the combustion process starts later, potentially causing incomplete combustion and higher pressure in the cylinder, which can result in knocking and decreased performance.

Answer: B) Leaking nozzle tip
Explanation: A leaking nozzle tip can cause uneven fuel delivery, leading to a rough engine idle and excessive exhaust smoke due to incomplete combustion.

Answer: C) To prevent backflow of fuel from the high-pressure side to the low-pressure side
Explanation: The delivery valve in scroll type fuel injection pumps prevents the backflow of fuel from the high-pressure side to the low-pressure side. This ensures that the fuel remains under pressure within the injection system, maintaining the correct amount of fuel delivered to the injector.

Answer: A) Nozzle tip
C) Needle valve
E) Spring
Explanation: In a cross section through the nozzle of a fuel injector, the main components typically include the nozzle tip, needle valve, and spring. The nozzle tip is where the fuel is ejected, the needle valve controls the opening and closing of the nozzle, and the spring helps maintain the correct position of the needle valve.

Answer: C) Leaking nozzle seals
Explanation: Leaking nozzle seals can allow fuel to continuously leak into the combustion chamber, leading to excess fuel consumption and potential engine damage.