Fuel Delivery
An electric fuel pump (located inside fuel tank) supplies fuel under pressure to throttle body. The ECM actuates the fuel pump through the fuel pump relay when the ignition is in the "ON" or "START" position. The fuel pump relay is located in relay panel. If engine stalls or is not cranked within one second after ignition is turned on, ECM will deactivate fuel pump.
The fuel pressure regulator is an integral part of the throttle body, and provides pressurized fuel at up to 20 psi. A diaphragm-operated relief valve regulates fuel pressure. Relief valve is exposed to atmospheric pressure on bottom side and top side, and senses fuel pressure to maintain constant pressure between 9 and 12 psi across fuel injectors. Unused fuel is returned to fuel tank through fuel return line.
During normal engine operation, 2 fuel injectors are actuated alternately by ECM. The injectors direct metered atomized fuel into throttle bores above throttle valves. Both injectors are actuated simultaneously during cranking. See Fig 1 .