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. Nozzle spray pattern is on a 25° angle, in a conical pattern. There are 2 "O" ring seals used. The lower "O" ring seals the injector at the intake manifold. The upper "O" ring seals the injector to the fuel rail.

The "O" rings should be lubricated and replaced whenever the injector is removed from the intake manifold. These "O" rings also 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. See Fig 1 . The injectors are identified with an ID number cast in the injector near the top. Injectors manufactured by Rochester Products have an "RP" positioned near the top 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 moveable armature is attached to the nozzle valve which is pressed against the nozzle body sealing seat by a helical spring.

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, or on time.

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.