High-pressure pump

A pump comprising:

• a housing;
• a driven member coupled to the housing;
• a head coupled to the housing and defining a first sealing surface, a valve bore having a first diameter, a plunger bore having a second diameter, and an intermediate chamber having a third diameter, the intermediate chamber being located between the valve bore and the plunger bore;
• a plunger configured to reciprocate within the plunger bore, the plunger, the plunger bore, and the intermediate chamber at least partially defining a pumping chamber;
• and
• a control valve assembly coupled to the head, the control valve assembly including an actuator moveable in response to an input signal and a valve element coupled to the actuator, the valve element being received within the valve bore and being moveable between an open position and a closed position and including a body having a fourth diameter and a valve head having a fifth diameter, the valve head including a second sealing surface;
• wherein when the valve element is in the closed position, the first sealing surface and the second sealing surface cooperate to form a sealed interface.