The fuel injector in a Hyundai Sonata mixes fuel with air under pressure and rendered carburetors obsolete during the late 1980s. One advantage of a fuel injector is the programmable firmware that allows the same hardware to work with different fuels. The fuel injector assembly includes only the nozzle and valve; it still requires a pump to deliver fuel into the engine.
Determine which fuel injector your Hyundai Sonata will need. This depends not only on the make and model, but also the engine size. Models made from 1998 to 2001 have the 2.4L Sirius or 2.5L Hyundai engine. Models manufactured from 2002 to 2005 have a 2.4L Sirius or 2.7L Hyundai engine. Models made after this date will be equipped with a 2.4L or 3.3L engine.
Relieve the fuel system pressure and disconnect the negative battery cable with a socket wrench.
Remove the air intake surge tank with a socket wrench, if needed, and disconnect the fuel lines and electrical connectors for the fuel injectors. Detach the vacuum hose for the fuel pressure regulator and lift out the fuel supply manifold with the injectors still attached. You may now separate the fuel injectors from the supply manifold and discard the old O-rings.
Install the fuel injectors to the fuel supply manifold using new O-rings. Use a torque wrench to tighten the mounting bolts for the fuel supply manifold to between 84 and 132 inch pounds.
Complete the remainder of the installation by reversing the removal procedure. Start the engine and check for leaks.
