What is the main function of a boost pump?

A boost pump's primary function is to supply fuel to the engine at the appropriate pressure, maintaining the optimal performance of the fuel system. While it is true that a boost pump can assist with fuel transfer between tanks, its main purpose is to provide a steady supply of pressurized fuel to the engine and ensure consistent fuel flow during operation.

When fuel is drawn from a tank, especially as fuel levels drop, the boost pump ensures that there is enough pressure to avoid vapor lock and maintain proper engine operation. Thus, its role is crucial for preventing fuel starvation, especially during high power demands or when fuel levels are low.

Other options mention roles that are not the primary function of the boost pump. For instance, regulating fuel pressure is more an aspect of fuel control units, initiating engine starts is typically managed by starter systems, and supplying fuel to the APU is typically handled by dedicated systems specific to auxiliary power units.