A dispensing pump (12) for a viscous liquid comprises a cylinder (16), a piston (24) mounted for reciprocation within said cylinder (16), an inlet (50) for admitting liquid to be dispensed into said cylinder (16) and a ball check valve (52) arranged selectively to open and close said inlet opening. The ball valve (52) is retained in position by a spring (58) having a variable diameter. The piston (24) has a dispensing passage (40) in fluid communication with said cylinder (16) and with a self sealing dispensing valve (38). The pump (12) further comprises a sliding cut-off valve (70) arranged selectively to open and close fluid communication between the piston dispensing passage (40) and the cylinder (16) as the piston (24) reciprocates within the cylinder (16).
