🔍 Key Concepts

• how a fuel injection nozzle and needle valve control the timing and amount of fuel entering the cylinder • what happens inside the cylinder if fuel continues to flow after the proper cut‑off point • symptoms and risks associated with over-fueling a cylinder (temperature, combustion, smoke)

💭 Think About

• Think about the normal function of the needle valve during injection and at the end of injection: what is it supposed to do? • If the needle valve cannot close, what will the fuel spray pattern and timing look like—shorter, longer, or stopped? • Which of the choices describes an effect that would logically result from fuel flowing when it should not stop, versus an effect that would come from fuel being blocked?

✅ Before You Answer

• Be sure which component handles fuel cut-off in the nozzle assembly • Ask yourself if a stuck-open valve would ever cause zero fuel flow through the nozzle, or the opposite problem: continuous/extended flow • Consider which listed effect is a direct consequence of continuous injection into the cylinder, not a secondary piping or timing issue