A fluid injector comprises a housing (1), a valve body (2) and an actuator unit (3) that is inserted into the housing (1). The valve body (2) comprises a cartridge (21) with a recess (211) that takes in a needle (22). The valve body further comprises a hollow body (23) which is arranged in a fixed position to the needle (22) and forms a first spring rest (231). The valve body further comprises a valve cap (26), which takes in the cartridge (21) and forms a second spring rest (261). A return spring (25) rests on one hand on the first spring rest (231) and on the other hand on the second spring rest (261). The valve cap (26), the housing (1) and the cartridge (21) are formed such, that before the valve cap (26) and the housing (1) and the valve cap (26) and cartridge (21) are permanently fixed to each other the valve cap is moveable relative to the housing (1) and the cartridge (21) while the housing (1) and the cartridge (21) stay in a fixed position relative to each other.