4.20. Check of functioning and replacement of fuel injectors

Fuel is extremely flammable therefore during the work with any part of fuel system take additional precautionary measures. You do not smoke and do not allow emergence near a working zone of naked flame and lamps without plafonds. Do not work in garages with the equipment on natural gas with a match (like heaters of water and dryers for clothes). At hit of fuel on skin immediately wash away it water with soap. When carrying out any works with fuel system use goggles and you keep in readiness the fire extinguisher.


Check on the car


  1. By means of a mechanical stethoscope (available in most shops of autoaccessories) check during the operation of the engine idling existence of clicks in each injector (watch an illustration).

If there is no mechanical stethoscope, to check clicks in injectors it is possible to check by means of the screw-driver. Establish the end of the screw-driver on an injector, and press the handle to an ear.

  1. During the work injectors create a steady sound of clicks.
  2. Increase engine turns higher than 3500 rpm. Frequency of clicks has to increase with engine turns.
  3. If the injector does not function (there are no clicks), get in shop of autoaccessories a special lamp for check of injectors and connect it to the electric socket of an injector. Start the engine and be convinced, resistance that the lamp blinks. It means that on an injector the correct tension therefore the injector is faulty arrives.
  1. Disconnect the socket of each injector and check resistance of injectors. Compare results with provided in the Size table and adjusting data at the end of the Management of values. Replace all injectors with the wrong value of resistance.

Check of volume

As conducting check of volume of an injector requires a special tester of an injector, this procedure is outside opportunities of a house workshop. Charge conducting check of volume of injectors to the dealer of BMW or other expert.



  1. Disconnect the main electric socket of a cable of fuel injectors. Remove the inlet pipeline (watch Honour the Repair work which is carried out without extraction of the engine from the car).
  1. Disconnect fuel hoses from the fuel highway and turn off bolts of fastening of the fuel highway (are shown by shooters).
  1. Remove from the inlet pipeline the fuel highway / injectors assembled.
  2. Installation back to removal. Do not forget to replace all rings of round section. For prevention of damage of rings at installation grease them with a thin layer of motive oil. Create pressure (establish a safety lock of the fuel pump and include ignition) in fuel system and before start of the engine check existence of leaks.