Mechanical fuel pump, pre1990 driven off the camshaft at the rear of the motor. These pumps are generally reliable but when a diaphragm goes bad it can be very bad as often raw fuel is pumped into the engine. This dilutes the oil and causes severe wear. When fitting make sure the pump lever is sitting on the cam lobe, not to the side.
See
AZX1818MS for our own super pump. For 1275cc engines from 1990 on a different pump
AZX1817 was used. Cars with HIF38 carb used
WND10005