Fuel Supply Device

A fuel supply device includes a sub-tank, a fuel pump, a transfer jet pump, a reduction valve, and a partition wall. The sub-tank is disposed within the fuel tank and forms a container configured to store fuel. The fuel pump is disposed in the sub-tank and is configured to pump fuel from the sub-tank. The transfer jet pump is configured to pump fuel from the fuel tank into the sub-tank. The reduction valve generates heat during operation. The partition wall divides an interior of the sub-tank into a first chamber and a second chamber. The fuel pump is disposed in the first chamber. Fuel passing through the reduction valve is discharged into the second chamber.