Coupling device for hydraulically and mechanically coupling a fuel injector to a combustion engine fuel rail, having a fuel injector cup with a central longitudinal axis hydraulically coupled to the rail and engaging a fuel inlet portion of the injector, a first ring element fixedly coupled to the cup, and a second ring element fixedly coupled to the injector. One of the ring elements has a collar arranged radially outside the other elements and extending from the one element in direction of the longitudinal axis. The collar has a recess facing the central longitudinal axis. A circlip is arranged in the recess and arranged and designed to form a positive fitting coupling between the first and second ring elements. The circlip prevents a movement of the first ring element relative to the second element retaining the fuel injector in the fuel injector cup in direction of the central longitudinal axis.