A dual fuel system includes a first pressurized fuel reservoir, a first fuel pump fluidly connected to the first pressurized fuel reservoir, a second pressurized fuel reservoir, and a second fuel pump including a pump outlet fluidly connected to the second pressurized fuel reservoir, a pumping chamber, an actuating fluid inlet fluidly connected to at least one of the first fuel pump or the first pressurized fuel reservoir, and at least one pumping element. The first fuel pump may have excess capacity, at least at times, so as to provide a pressurized first fuel for actuating the second fuel pump. The at least one pumping element may include an intensifier or de-intensifier plunger such that a flow rate of a second pressurized fuel from the second fuel pump is different than a flow rate of the first pressurized fuel from the first fuel pump as an actuating fluid for the second fuel pump. Related apparatus and methodology is also disclosed.