5.2.21. Nozzles

In the Common Rail system special nozzles with hydraulic strengthening and an electric element of start-up (the solenoidal valve) for ensuring giving of the necessary amount of fuel in the combustion chamber are used.

For ensuring exact amount of injectable fuel opening of a nozzle has to happen very quickly that demands giving of ECU of high voltage. After full opening of a needle of a spray the current brought to the solenoidal valve decreases up to the size sufficient for deduction of the solenoidal valve in open situation. The amount of injectable fuel is defined by the period of opening of a spray and pressure in system. After interruption in supply of tension to the solenoidal valve the needle of a spray falls down and hermetically blocks supply of fuel under high pressure in the combustion chamber.

Functioning check


  1. Using current-measuring pincers of the device for check of the engine, check functioning of fuel nozzles. Current-measuring pincers have to conform to the following requirements:
    1. range of measurements more than 25 And;
    2. frequency range is more than 100 kHz.
  1. Connect the socket to a nozzle. Establish current-measuring pincers around a nozzle head, start the engine in the mode of idling and measure the current consumed by a nozzle, and compare a current curve to the curve given on the drawing.
  • The size of a phase of consumption of current (at most 12 And) depends on the frequency of rotation of a bent shaft of the engine.
  • The first site of a curve shows preliminary injection of fuel.
  1. Check a nozzle for fuel injection. Disconnect the socket from a nozzle and connect to an additional nozzle.
    If at the same time operation of the engine did not change, the checked nozzle does not inject fuel.
    If operation of the engine changed, so the checked nozzle is serviceable and injects fuel.
    This check does not allow to establish amount of the fuel injected by a nozzle.
    If necessary replace all fuel nozzles.
  2. At the switched-off ignition measure supply voltage on contacts 33 (cylinder No. 1), 36 and 39 (cylinder No. 3), 40 (cylinder No. 2) and 37 ECM. Tension: 0 Century.
  3. If tension does not correspond to demanded, check a condition of an electrical wiring. If the electrical wiring is serviceable, replace ECM.

Measurement of resistance


  1. Disconnect the electric socket from a nozzle.
  1. Measure resistance between contacts of the socket. Resistance: 0,3–0,6 Ohms at a temperature of 20 °C.
  1. Connect the electric socket to a nozzle.