Fuel injector is an electronically controlled solenoid gadget, which is operated by PCM and measures the amount of fuel under pressure supplied to one cylinder at a time. When energized a normally closed bail valve opens and this makes the fuel pass through a director plate to the injector outlet in which there are special holes which regulate the fuel supply to give a twin conical spray pattern of finely atomized fuel to the intake valves for further vaporization before getting into the combustion chamber. There are numerous driveability conditions that can be experienced when injectors do not open or are stuck open, leaking injectors and injectors with low coil resistance. Hot soak deposits on the fuel system could cause certain driveability problem that may be as a result of bad fuel quality or driving habits that sees fuel left in the injector tip to dry and deposit themselves on the walls andcone with a resultant change in spray patterning leading to low power, unstable idle, difficult starts and low fuel economy. Injector testing is done normally with the engine running, by placing a mechanic's stethoscope or a screwdriver on the solenoid to confirm on their working. When all injectors click but there is still poor driveability, then the following tests must be run, fuel rail pressure test and cylinder drop test to quantify poor cylinder output. Whenever there is clicking associated with injections, and the ignition system is good, the proper diagnosis of the suspect injector will require bench testing for spray pattern. In case of non-working injectors, the circuit can be tested with the help of a 'noid' light; if the light does not blink, the circuit may be bad and the mechanic must check the harness and the PCM. Depend on the kind of engine, where possible removal and installation of injectors are: Firstly, the negative battery cable must be disconnected and the fuel system pressure relieved, then the air cleaner assembly and fuel rail are to be removed and the electrical connectors disconnected and the injector twisted out. New injector O-ring seals needs to be lubricated before being fitted and electrical connectors has to be oriented correctly before assembling fuel rail and checking for any leaks on relaunching the fuel pump.
