A temporary fuel supply system for a vehicle that can temporarily circumvent the vehicle's inherent system. The temporary fuel supply system has a fuel input port for receiving fuel and a fuel output port for discharging fuel. The fuel supply system also includes at least one fuel storage container to store fuel, provide fresh fuel and/or store contaminated or old fuel. Inside the system, a pump, pressure regulator, and fuel filters are provided. A first three-way valve selectively connects the second three-way valve to either the fuel input port or to a fuel storage container. A second three-way valve selectively connects the pump to either the first three-way valve or to a fuel storage container. Depending upon how the valves are controlled, the fuel supply system can draw and transfer fuel in a variety or manner to achieve different purposes.