Fuel Injectors
A fuel injector is installed in the intake manifold at each cylinder. Mounting is approximately 1.7-2.5" (70-100 mm) from the center line of the intake valve on V6 and V8 applications. Nozzle spray pattern is on a 25° angle. There are 2 "O" ring seals used. The lower "O" ring seals the injector at the intake manifold.
The "O" rings are lubricated and replaced as necessary whenever the injector is removed from the intake manifold. The "O" rings provide thermal insulation, thus preventing the formation of vapor bubbles and promoting good hot start characteristics. The "O" rings also prevent excessive injector vibration.
Air leakage at the injector/intake area would create a lean cylinder and possibly a driveability problem. A second seal is used to seal the injector to the fuel rail connection. See Fig 1 . The injectors are identified with an ID number cast on the injector near the top side. Injectors manufactured by Rochester Products have an "RP" positioned near the top side in addition to the ID number.
The solenoid-operated injector consists essentially of a valve body and a nozzle valve which has a special ground pintle. The movable armature is attached to the nozzle valve which is pressed against the nozzle body sealing seat by a helical spring. At the back of the valve body is the solenoid winding and in the front section is the guide for the nozzle valve.
Each injector has a 2-wire connector. On 3.0L and 3.8L motors, the engine connectors have a spring clip that must be released (unlocked) before removal of the connector. One wire supplies voltage from the fuse(s) in the fuse panel. The second wire connects to the ECM, which controls the ground to operate the injectors (pulse width).
The electric pulses generate a magnetic field in the solenoid winding. As a result, the armature is drawn back and lifts the nozzle valve from its seat approximately .038" (.15 mm). The helical spring closes the nozzle valve.