The invention relates to a fuel injector (18) including a central longitudinal axis (L) and being operable to be arranged in a cylinder head (14) of a combustion engine (22) . The fuel injector (18) has an injector body (26) and an adjustment device (30), the adjustment device (30) comprising a ring element (32) being designed to be arranged in a recess (15) of a cylinder head (14) between the injector body (26) and the cylinder head (14) to align the fuel injector (18) relative to the recess (15) in radial direction. The ring element (32) comprises a magnetic material. The invention relates to a fuel-injection system with a cylinder head (14) of an internal combustion engine (22) and a fuel injector (18).