Abstract: A fuel injection pump of the reciprocable plunger type has a pump plunger which is slidable within a pump barrel about which is mounted an angularly movable sleeve. The sleeve and plunger are interconnected so that they can move axially relative to each other but are restrained against relative angular movement. An arm is coupled to the sleeve its inner end lying within a slot in the sleeve, the arm being provided with limbs which lie within a circumferential groove, the arms embracing the sleeve to retain the inner end of the arm within the slot.