Fluid transfer devices with fluid bypass and ambulatory infusion devices including same

Fluid transfer devices for use in, for example, ambulatory infusion devices, and infusions devices including such fluid transfer devices. The fluid transfer devices may include an external housing tube, an internal housing tube that has a piston lumen with a pump chamber, an outer surface, and a bypass aperture with an inlet associated with the pump chamber and an outlet adjacent to the outer surface, a bypass channel in fluid communication with the bypass aperture outlet, a resilient valve member associated with the bypass aperture outlet, and a piston carried within the piston lumen.