An inflatable penile prosthesis includes an implantable pump having a bypass valve. The bypass valve includes a cavity having a valve seat at a port, a poppet and a spring. The poppet includes a valve member and a stem extending from the valve member. In operation, the poppet includes a sealing position, where the valve member seals the port through contact with the valve seat, and a deflating position, where the valve member is displaced from the valve seat. The spring is configured to bias the valve member toward the valve seat, wherein the spring engages a portion of the stem while the poppet is in the deflating position.
