Abstract: An electromagnetic pump particularly adapted for use with oil burners is disclosed. The pump embodies an armature that is reciprocated by a magnetic field produced by an electromagnetic coil. The armature drives the piston of a piston pump that is adapted to pump a liquid at low volume and high pressure. The pump also embodies a diaphragm disposed in a chamber having an inlet portion on one side of the diaphragm and an outlet portion on the other. The inlet portion of the chamber is connected to a liquid supply line leading to the pump and the outlet portion is connected to the discharge of the piston pump and also to a valve-controlled vent leading to atmosphere. The diaphragm is moved in one direction only by the armature and in the opposite direction by a spring. When there is air in the liquid supply line, the vent valve is opened and the diaphragm rapidly pumps air to the atmosphere. When liquid is discharged from the vent, the valve is closed.