FUEL PUMP

A drive arrangement for a plunger operated fuel pump including said arrangement including a pump plunger adapted to reciprocate along a first axis, and being driven by a rotating cam in contact with one end of said plunger, and where said cam and said contact end of said plunger are located in a cambox housing, characterised wherein said housing includes a bore, within which is located a compensating plunger arrangement, one end of which is adapted to contact said cam, such that the cam provides reciprocating movement to said compensating plunger.