Fuel pump

aaaaaaFuel pump may comprise a casing and a substantially disc-shaped impeller which is rotatably disposed within the casing. A first group of concavities may be formed in a lower face of the impeller. A second group of concavities may be formed in an upper face of the impeller. A first groove may be formed in the inner face of the casing opposite the upper face of the impeller. The first groove is formed in a region opposite the first group of concavities and extending from an upstream end to a downstream end. A second groove may be formed in the inner face of the casing opposite the lower face of the impeller. The second groove is formed in a region opposite the second group of concavities and extending from an upstream end to a downstream end. Preferably, the depth of the first and second groups of concavities and the depth of the first and second grooves are adjusted such that the flow of fuel flowing through the first group of concavities and the first groove is greater than the flow of fuel flowing through the second group of concavities and the second groove.