120 F2B ENGINE T RAKKER E URO 4/5 Base q November 2006 Print 603.93.641 Injector-pump Figure 245 44908 1. Fuel/oil seal q 2. Fuel/diesel seal q 3. Fuel/exhaust gas seal The injector-pump is composed of: pumping element,nozzle, solenoid valve. Plunger The plunger is operated by a rocker arm governed directly by the cam of the camshaft. The plunger is able to ensure a high delivery pressure. The return stroke is made by means of a return spring. Nozzle Garages are authorized to perform fault diagnosis solely on the entire injection system and may not work inside the injector-pump, which must only be replaced.
A specific fault-diagnosis program, included in the control unit, is able to check the operation of eac h injector (it deactivates one at a time and checks the delivery of the other five). Fault diagnosis makes it possible t o distinguish errors of an electrical origin from ones of a mechanical/hydraulic origin. It indicates broken pump-injectors. It is therefore necessary to interpret all the control unit error messages correctly. Any defects in the injectors are to be resolved by replacing them. Solenoid valve The solenoid, which is energized at each active phase of the cycle, via a signal from the control unit, controls a slide valve that shuts off the plunger delivery pipe.
When the solenoid is not energized, the valve is open, the fuel is pumped but it flows back into the return pipe with the normal transfer pressure of approximately 5 bars. When the solenoid is energized, the valve shuts and the fuel, not being able to flow back into the return pipe, is pumped into the nozzle at high pressure, causing the needle to lift. The amount of fuel injected depends on the length of time the slide valve is closed and therefore on the time for which the solenoid is energized. The solenoid valve is joined to the injector body and cannot be removed. On the top there are two screws securing the electrical wiring from the control unit.
To ensure signal transmission, tighten the screws with a torque wrench to a torque of 1.36 q 1.92 Nm (0.136 q 0.192 kgm). 775010 Replacing injectors-pump Injectors have to be replaced with great care (for their removal see the description on pages 51 and 52, for fitting them see the description on pages 93 and 94). NOTE If this job is done with the engine on the vehicle, before removing the injectors-pump drain off the fuel contained in the pipes in the cylinder head by unscrewing the delivery and return fittings on the cylinder head. Figure 246 0 411 700 002 XXXXXX XXXX X 868 USA / 87060 For each replaced injector, connect to MODUS or IT2000 station or to E.A.SY:
then, when required by the program, enter the code, that is stamped on the injector ( ), for reprogramming the central unit. NOTE When checking the clearance of the rocker arms, it is important to check the injector-pump pre-load.