Engine fuel-injection pump with reciprocating plunger

摘要

At the top end of the recess (21) towards the chamber (11) and at the opposite side to the opening (25) an air vent (39) formed in the barrel leads to a vent passage (41) in the pump housing, This is in turn connected to the fuel return pipe from the latter. The vent can be formed by a drilling, or alternatively a lengthwise slot, in the barrel wall. The vent passage (41) can be at right angles to the plunger axis, a spill port in each barrel leading into it.