<p>A vehicle fuel supply device including a saddle-shaped fuel tank which is comprised of a main chamber and an auxiliary chamber. A reservoir (17) is disposed within the main chamber (13). A main pump (21) is provided within the reservoir. A sub-pump (22) is detachably provided within the reservoir. The fuel in the reservoir is drawn up by an operation of the main pump to supply fuel to an engine (15). A portion of the drawn-up fuel is utilized to generate a negative pressure, the negative pressure is utilized to transfer the fuel in the auxiliary chamber (14) to the reservoir, and the negative pressure is utilized to introduce the fuel in the main chamber into the reservoir.</p>
