Abstract: A single stage centrifugal fuel pump which can provide a large range of flow, 1 to 300 gpm, while maintaining low flow, high speed operation with pressure instability at minimum values comprises a radial-flow impeller having a front shroud and a discharge for discharging fuel from the impeller. A diffuser ring has a throat entrance located opposite and in spaced relation to the discharge of the impeller. The front shroud is provided with an extension which extends into the vaneless space between the impeller discharge and the throat entrance of the diffuser ring thereby reducing the flow at which pressure instability inception occurs.