A vehicle includes a direct start engine, an automatic transmission having a threshold fluid pressure sufficient for enabling operation of the transmission when the engine is off, a controller, and a fuel delivery system. The controller determines the presence of predetermined engine states, and optimizes a stop-and-go functionality of the engine. The fuel delivery system includes a motor and an integrated pump assembly having a secondary high-pressure (HP) fuel pump which is selectively connectable to a rotatable shaft of the motor, and a secondary low-pressure (LP) fluid pump which is continuously connected to the shaft. The motor continuously energizes the secondary LP fluid pump via the rotatable shaft to thereby maintain the threshold fluid pressure during a first or second engine state, and selectively energizes the secondary HP fuel pump via the rotatable shaft to maintain the threshold fuel pressure during the second engine state.