A portable system for transferring liquids such as fuels from a first tank to a second tank. The first tank may be, for example, a railcar and the second tank a transport trailer. The portable system is separated into multiple compartments with an engine compartment and a pump compartment. A wall separates the engine and pump compartments and may be sealed to prevent the passage of air or vapor therethrough. The pump is utilized to transfer liquid from the first tank to the second tank.