MDE 5 End of Unit Quiz

Answer: B) Poor injector atomization
Explanation: Poor injector atomization can lead to incomplete combustion of the fuel, reducing fuel efficiency and increasing fuel consumption.

Answer: B) It increases the spray pattern's spread and improves atomization
Explanation: High fuel pressure improves the atomization of the fuel by forcing it through the nozzle more forcefully, which increases the spray pattern’s spread and enhances mixing with air for better 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: 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: B) To inject fuel into the combustion chamber at high pressure
Explanation: The primary function of a diesel engine fuel nozzle is to inject fuel into the combustion chamber at high pressure, ensuring proper atomization and mixing with air for efficient combustion.

Answer: B) To ensure the fuel mixes thoroughly with air for efficient combustion
Explanation: Fuel atomization is important because it breaks the fuel into fine droplets, allowing it to mix thoroughly with air in the combustion chamber. This promotes efficient combustion and better engine performance.

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) By using a pressure relief valve to divert excess fuel
Explanation: In scroll type fuel injection pumps, a pressure relief valve is used to divert excess fuel if the high-pressure pipe fails. This valve prevents fuel from spraying out by redirecting it, thus protecting the system and maintaining safety in the event of a pipe failure.

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: 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: C) By varying the displacement of the scroll mechanism
Explanation: In a scroll type fuel pump, fuel metering for high and low loads is achieved by varying the displacement of the scroll mechanism. This adjustment changes the volume of fuel pumped, allowing the pump to deliver the appropriate amount of fuel for different engine loads and operating conditions.

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.