BMW 335i xDrive Fuel Injector Replacement at your home or office.

How do mechanics replace a fuel injector?

Injectors can be serviced once removed from the car or replaced outright with new injectors. If the injectors are serviced, specialized cleaning and test equipment are required. The choice to repair versus replace will depend on exactly what is wrong with the injector as well as customer preference. Either option requires removing the injector from the car and the following procedure is typical:

• Once the engine is cold, the pressure within the fuel rail is relieved by briefly running the engine with the fuel pump fuse out.
• The upper plenum on the intake manifold is removed along with any cables, hoses, or wiring that restricts access.
• The supply and return lines are removed from the fuel rail. The electrical connectors to each fuel injector are unlocked and removed. The fuel rail is then unbolted and removed from the intake manifold.
• The injector(s) requiring replacement are removed from the fuel rail, taking care to not allow any debris to enter the exposed openings. An O-ring seal usually holds the injector very firmly in a finely polished bore in the fuel rail.
• Using a new O-ring, the serviced or replaced injector is re-inserted into the fuel rail — using engine oil on the O-ring to prevent damaging it. O-rings in this application fit very tight to prevent fuel leaks.
• The fuel rail is re-installed and the supply and return lines are re-connected. The plenum is re-installed along with all cables, hoses, or wiring.
• Finally, the engine is run, there is a careful check for leaks, and the vehicle is road tested.