Fuel Delivery
A high pressure electric fuel pump, located inside fuel tank, supplies fuel to the injectors. The pump receives power through starter relay, fuel pump relay, and EEC power relay. When ignition switch is turned to "ON" position, EEC power relay is activated, closing EEC power relay contacts. Power is provided to fuel pump relay and to a timer within the EEC module. If the ignition switch is not turned to the "START" position within 1 second, the EEC module timing device will deactivate the fuel pump relay. When the fuel pump relay is activated, fuel pump operates on low voltage. The fuel pump is deactivated when fuel pump relay is deactivated. This circuitry provides pre-pressurization of the fuel system.
When the ignition switch is turned to the "START" position, starter relay is energized. This relay provides power to starter motor and fuel pump, by-passing the fuel pump relay. This circuit provides full system voltage to fuel pump during cranking modes.
After the engine starts and the ignition switch is returned to "ON" position, power to fuel pump is again supplied through fuel pump relay. The EEC module senses engine RPM and deactivates the fuel pump when engine stops or engine speed falls below 120 RPM.
The inertia switch, located in the trunk, is designed to open the fuel pump power circuit in the event of a collision. This switch is reset by pushing both buttons on switch simultaneously. The switch should not be reset until fuel system has been inspected for damage or leaks.
Fuel is pumped through fuel filters to the fuel injectors and pressure regulator mounted on throttle body. The fuel pressure regulator controls fuel pressure to 39 psi (2.74 kg/cm2 ) across the fuel injectors. Fuel in excess of that used to maintain constant pressure is returned to fuel tank through the fuel return line.
Injectors are actuated, spraying calculated amount of fuel into engine, at twice the crankshaft speed. Only open time varies to satisfy fuel requirements.