A fuel injector is installed in the intake manifold at each cylinder. Mounting is approximately 70-100mm from the center line of the intake valve on V6 and V8 engine applications. The nozzle spray pattern is on a 25 degree angle. The fuel injector is a solenoid operated device controlled by the ecm. The ecm turns on the solenoid, which opens the valve which allows fuel delivery. The fuel, under pressure, is injected in a conical spray pattern at the opening of the intake valve. The fuel, which is not used by the injectors, passes through the pressure regulator before returning to the fuel tank.
An injector that is partly open, will cause loss of fuel pressure after the engine is shut down, so long crank time would be noticed on some engines. Also dieseling could occur because some fuel could be delivered after the ignition is turned to off position.
There are 2 O-ring seals used. The lower O-ring seals the injector at the intake manifold. The O-rings are lubricated and should be replaced 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 excess injector vibration.
Air leakage at the injector/intake area would create a lean cylinder and a possible driveability problem. A second seal is used to seal the fuel injector at the fuel rail connection. 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.