Which type of fuel pump requires a fuel pressure relief valve?

The positive-displacement fuel pump requires a fuel pressure relief valve because it can generate high pressure when there is no adequate flow of fuel to absorb the pressure increase. In a positive-displacement pump, the volume of fuel being displaced increases the pressure in the system, which can lead to damage if there’s no relief mechanism. The relief valve allows excess fuel to bypass back to the tank or system input to maintain safe operating pressures.

While centrifugal fuel boost pumps are designed to maintain a consistent flow of fuel and typically operate at lower pressures, they do not require a pressure relief valve in the same way. This is due to their different operational principles, as they rely on fluid dynamics and are less prone to the high-pressure concerns seen in positive-displacement pumps. Thus, the need for a pressure relief valve is a characteristic specific to positive-displacement pumps in fuel systems.