What is a common sign that a fuel pump is failing?

A common sign that a fuel pump is failing is difficulty starting the engine or sputtering during operation. When the fuel pump is not functioning properly, it may fail to deliver enough fuel to the engine. This inadequate fuel supply can lead to various performance issues, including hard starting or stalling. Sputtering can occur if the fuel delivery is inconsistent or if the pump is unable to maintain the required fuel pressure, which is essential for the engine to run smoothly.

The other options indicate good functionality and performance in a fuel system. For instance, an engine running smoothly suggests that all components, including the fuel pump, are operating correctly. Consistent fuel pressure is essential for engine performance, and clear exhaust emissions indicate complete combustion, often signifying that the fuel system, including the pump, is functioning well. In contrast, the presence of starting difficulties or sputtering during operation highlights specific failures or issues associated with the fuel pump's ability to supply fuel effectively.