Fuel Delivery
An electric in-tank fuel pump, supplies pressurized fuel to the throttle body. The ECM actuates the fuel pump through a fuel pump relay when ignition is turned on. If engine is not started within 2 seconds, the ECM will deactivate fuel pump until engine is started.
As a back-up system to fuel pump relay, the fuel pump can also be activated by an oil pressure switch. The oil pressure switch is normally open until oil pressure reaches approximately 4 psi (.28 kg/cm2 ). If fuel pump relay fails, the oil pressure switch closes when oil pressure is obtained, operating the fuel pump. Inoperative fuel pump relay may result in extended cranking times.
The fuel pressure regulator, an integral component of the throttle body, provides proper pressurized fuel under all operating conditions. A spring/diaphragm-operated relief valve regulates fuel pressure. Relief valve is exposed to atmospheric pressure, maintaining constant pressure of 9-12 psi (.6-.8 kg/cm2 ) across fuel injectors. Excess fuel is returned to fuel tank through fuel return line.
During normal engine operation, 2 fuel injectors are actuated alternately by the ECM. The injectors direct metered atomized fuel into throttle bores above throttle valves. Both injectors are actuated simultaneously during cranking.