Which of the following is a symptom of a failing fuel pump?

A failing fuel pump can lead to various symptoms that affect engine performance. Difficulty starting the engine is common because the fuel pump is responsible for delivering gasoline from the tank to the engine. If the fuel pump is not functioning properly, it may not supply adequate fuel pressure, making it harder to start.

Additionally, stalling and reduced engine power are also significant indicators of a failing fuel pump. When the fuel pump cannot maintain the necessary pressure, the engine may struggle to receive enough fuel during acceleration, leading to a loss of power. This can cause the engine to stall if the fuel supply becomes too inadequate.

In contrast, increased fuel efficiency, consistent idle speed, and clear exhaust emissions are not typical symptoms associated with a failing fuel pump. These characteristics usually indicate that the engine and fuel delivery system are functioning properly. Therefore, the presence of difficulty starting, engine stalling, and reduced engine power clearly points to an issue with the fuel pump's ability to deliver the necessary fuel to the engine.