What is the function of the fuel lift pump?

The function of the fuel lift pump is essential for the proper operation of a diesel engine. It is responsible for drawing fuel from the fuel tank and supplying it to the injection pump. This process is crucial because the injection pump needs a pressurized supply of fuel to ensure that it can deliver the appropriate amount of fuel at the correct pressure to the engine's fuel injectors.

If the lift pump were not functioning effectively, it could lead to inadequate fuel supply to the injection pump, causing performance issues such as sputtering, stalling, or failure to start. By maintaining a consistent fuel flow under pressure, the lift pump plays a vital role in preparing the fuel for the combustion process that occurs in the cylinders.

The other functions listed, such as compressing air, filtering fuel, or injecting fuel directly into the cylinders, pertain to different components of the diesel fuel system. Each of those functions is performed by other systems or parts, illustrating the specific and critical role of the fuel lift pump in the overall operation of a diesel engine.