A pressurisation pump is provided comprising a first plunger and a second plunger, each plunger being reciprocable within a respective plunger bore defined by a housing, wherein the first and second plungers together with the bores define, at least in part, a pumping volume. The pump also includes an inlet port and an outlet port. An end of the first plunger is arranged to cover the inlet port during a pump delivery stage in which fluid is displaced from the pumping volume and an end of the second plunger is arranged to cover the outlet port during a pump fill stage in which fuel is drawn into the pumping volume. The end of the first plunger and the end of the second plunger are arranged to cover the inlet port and the outlet port respectively during a pump transfer stage during which the pumping volume is maintained.