INJECTOR OPERATION
Oil Pressure
Fuel Pressure
High Pressure Oil
Atmosphereic Pressure
Fuel Supply Pressure
Above 3100 PSI
Fill
• During the fill stage, the spool valve is in
the closed position. High pressure oil from
the oil rail cannot pass through the
spool valve.
• Low pressure fuel passes through the fuel
inlet check valve and fills the plunger cavity.
• The needle control spring holds the needle
on its seat so that fuel cannot enter the
combustion chamber.
Oil Pressure
Fuel Pressure
High Pressure Oil
Atmosphereic Pressure
Fuel Supply Pressure
Above 3100 PSI
Injection
• The injector drive module energizes the
open coil, and the spool valve moves to the
open position. The Injector Drive Module
turns off the current to the coil, but the
spool remains in the open position.
• High pressure oil flows to the intensifier
piston. Fuel pressure builds when the
plunger moves downward. The fuel inlet
check ball seats due to an increase in fuel
pressure under the plunger.
• When fuel pressure rises above the valve
opening pressure, the nozzle needle lifts
off its seat and injection begins.
58
International
®
VT 275 V6 Engine
