Repair manual

73547
104243
73548
Figure 3
Figure 4
Figure 5
A. Fuel inlet — B. Fuel delivery — C. By-pass nut —
D. Fuel return from the pump-injectors —
E. Pressure relief valve — Opening pressure: 5 - 5.8 bars.
CROSS-SECTION OF THE FUEL PUMP
1. Oil and fu el leakage indicator.
Injector-pump
1. Fuel/oil seal — 2. Fuel/diesel seal — 3. Fuel/exhaust gas seal.
The injector -pump is composed of: pumping element, nozzle,
solenoid valve.
Pumping element
The pumping element is operated by a rocker arm governed
directly by the cam of the camshaft .
The pumping element is able to ensure a high delivery
pressure. The return stroke is made by means of a return
spring.
Nozzle
Garages are aut horized 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 each injector (it
deactivates one at a time and checks the delivery of the other
five).
Fault diagnosis makes it possible to distinguish errors of an
electrical origin from ones of a mechanic al/hydraulic origin .
It indicates broken pump-injectors.
It is therefore necessary to interpret all the control unit error
messages correct ly.
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 pumping element 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
wrenchtoatorqueof1.36—1.92Nm(0.136—0.192kgm).
Fuel pump
SECTION 2 - FUEL
5
F3C CURSOR ENGINES
Print P2D32C005 E Base - May 2007