Electronic fuel injectors for all gasoline engine applications are basically the same. They consist of an injector body, an electric solenoid, spring, nozzle and a filter. The injector receives a constant supply of pressurized fuel from the fuel system. The primary function of the fuel injector is to atomize gasoline into the surrounding air, at the proper time. Throttle body injectors atomize fuel into the intake manifold in much the same manner as a conventional carburetor (wet intake). Port fuel injectors direct the atomized fuel at the backside of each cylinder's intake valve(s) (dry intake). Gasoline direct injection systems operate at substantially higher pressure and direct the atomized fuel directly into the combustion chamber of each cylinder.
Two of the most import diagnostic checks, when dealing with a driveability problem involve the ignition and the fuel systems. The questions most technicians attempt to answer first are "is there spark?'' and "is there fuel?'' This often leads to solving most basic problems. For ignition system diagnostic testing, please refer to the information on engine electrical components and ignition systems found earlier in this manual. If the ignition system checks out (there is spark), then you must determine if the fuel system is operating properly (is there fuel?).