Page 103 of 330

Marea-Marea Weekend 9 -™ Engine
2000 range (j§) Fuel feed system
10.
I I TEST
4F017XJ01
A switch (1) on the brake pedal con
trols the car brake lights; the same
switch sends a signal to pin 59 of the
injection control unit
The control unit uses the "brake pedal
depressed" signal to:
- detect a situation of over-run;;
- check the plausibility of the signal
from the accelerator potentiometer
CLUTCH PEDAL SWITCH
A switch (2) on the clutch pedal is connected to pin 61 of the injection control unit.
The injection control unit uses the "brake pedal operated" signal to distinguish gear engaged and gear
shift conditions.
PRESSURE RELIEF SENSOR
The sensor is fitted to the intake manifold and
the signal sent to the injection control unit is
used to:
- regulate injection pressure;
- regulate injection duration.
The figure alongside shows the sensor and
electrical connector with the following pin-
out:
1. pressure signal
2. Earth
3. Fuel feed system
ATMOSPHERIC PRESSURE SENSOR
The atmospheric pressure signal is built into the injection control unit. It is responsible for measuring at
mospheric pressure in order to correct measured air flow and reference air flow values to control the EGR
function.
Copyright by Fiat Auto 17
Page 106 of 330

Engine
Fuel feed system
JTD Marea-Marea Weekend @
2000 range ©
10.
7^ £3
PRESSURE PUMP
The pressure pump is radialjet type with three
radial pistons (total capacity 0.657 cc). It is
controlled by a timing belt with or without
timing requirements.
Each pump unit consists of:
a piston (5) opered by a cam (2) integral with
the pump shaft (6);
a plate-type intake valve (3);
a delivery ball valve (4).
The pressure pump must be supplied at a
pressure of at least 0.5 bars; and for this rea
son the fuel system is equipped with an aux
iliary pump submerged in the tank.
The pressure pump is lubricated and cooled
by the diesel fuel via channels and is able to
deliver a maximum pressure of 1350 bars.
1.
2.
3.
4.
5.
6.
7.
8.
Cylinder
Cam
Plate-type intake valve
Ball-type delivery valve
Piston
Pump shaft
Diesel intake connection -
from fuel filter
Diesel delivery connection
to manifold (rail)
Diesel delivery connection
recirculation
low pressure
high pressure
low pressure
PRESSURE REGULATOR
FILTER
The fuel pressure regulator is fitted to the
pressure pump and controlled directly by the
injection control unit. It regulates fuel feed
pressure to the injectors.
The pressure regulator consists mainly of the
following parts:
1. Ball plunger
2. Pin
3. Valve
4. Preload spring
5. Coil
6. Body
7. Anchor
20 Publication no. 506.763/24
Page 108 of 330

Engine
Fuel feed system
Marea- Marea Weekend W)JTD
2000 range ©
INERTIA SAFETY SWITCH
To increase car occupant safety in the case of
impact, the car is fitted with an inertia switch
located inside the passenger compartment se
cured to the inside of the left panel.
This sensor reduces the possibility of fire (due
to emerging fuel) by deactivating the auxiliary
fuel pump that supplies the injection circuit.
The switch consists of a steel ball, fitted in a
tapered housing, kept in place by the attrac
tion force of a permanent magnet.
In the case of violent impact, the ball is released from the magnetic detent and opens the normally closed
(NC) electrical circuit to cut off the auxiliary fuel pump connection to earth, and as a consequence the
supply to the injection system.
To restore the auxiliary pump earth connection, move back the seat and press the switch until a click is
heard.
Even after an apparently slight impact, if there is a smell of fuel or there are leaks from the fuel
system, do not turn the switch back on, but search for the fault and remedy it to prevent the risk
of fire.
'N.C. N.A. C
Inertia switch components
1. Inertia switch assembly
2. Sheath
3. Button
4. Upper side
5. Engagement side
6. Permanent magnet
7. Permanent magnet seat
8. Steel ball
C Common terminal
N.C. Normally closed contact
N.A. Normally open contact
22 Publication no. 506.763/24
Page 112 of 330

Engine
Fuel feed system
JTD Marea- Marea Weekend 9
2000 range @
10.
Operation at high rotation speeds
When the engine speed is increased, the ki
netic energy of the exhaust gases increases
gradually.
As a result, the speed of the turbine (5) in
creases and consequently the supercharging
pressure.
The VGT solenoid valve (2) operated by the
injection control unit (1), through the actuator
(4) causes the moving vanes to change posi
tion until the maximum opening position is
reached.
1. Injection control unit
2. VGT solenoid valve
3. Vacuum reservoir
4. Pneumatic actuator
5. Turbine
There is therefore an increase in the passage
sections and consequently a slowing down in
the flow of exhaust gases which pass through
the turbine (1) at the same speed or slower
than the low speed conditions.
The speed of the turbine (1) decreases and
settles down at a suitable vaule for the correct
operation of the engine at high speeds.
1. Turbine
2. Moving vanes
3. Pneumatic actuator
4. Rotary seal
TURBOCHARGER (1910 JTD 100 CV)
It basically consists of two impellers (1) on
one shaft (2) which rotates on floating bear
ings lubricated by a duct (3) from the engine
lubrication circuit.
The oil used dissipates some of the large
amount of heat given off by the exhaust gases
at the turbine.
There is a waste gate valve (4) fitted on the
turbocharger, operated by a pneumatic actua
tor (5), that makes it possible to shutter the
flow of exhaust gases to the turbine, accord
ing to the engine power/torque requirements.
The pneumatic actuator is controlled by the en
gine management control unit via a solenoid
valve.
* The turbocharger used on the 1910 JTD 100 CV version is the fixed geometry type.
26 VI 0^ Cam.frtfi and ri!plact<& Print n° 506.763/25
Page 122 of 330
Engine
Fuel feed system
Marea- Marea Weekend @ ™
2000 range ©
PRESSURE REGULATOR
NOTE During the operations of removing-
refitting the pressure regulator, work
in extremely clean conditions.
Removing
- If the vehicle is equipped with a shield un
der the engine, remove it.
1. Remove the engine oil filler plug (1), then
undo the fixing nuts (2) and remove the
sound insulation cover (3).
2. Undo the bolts (1) fixing the retaining
bands for the injector wiring.
Disconnect the electrical connectors (2) for
the injectors and place the wiring to the
side.
- Release the injection cable loom from the
retaining bands.
3. Undo the nuts (1) fixing the fuel return
manifold pipe (2) to the intake manifold.
Place the fuel return manifold pipe to the
side.
4. Disconnect the electrical connector (1) for
the pressure regulator, then undo the bolts
(2) fixing the regulator to the pump.
36 Print n° 506.763/25
Page 131 of 330

Marea- Marea Weekend
2000 range ©
Electrical equipment
Protection and security devices
55.
PROTECTION AND SAFETY DEVICES
All the vehicle supply lines were designed taking into account the most up-to-date directives in terms of
safety and protection, especially to prevent fires.
There are 2 types of protection:
- active protection, aims to reduce the causes of faults "at source"
- passive protection, aims to limit the effects of a fault as much as possible
The first category includes a carefully designed wiring layout with wires positioned and carefully anchored
on tracks that are repaired and protected if necessary.
The cables connected to the alternator and the motor were modified for this reason by adding protective
caps etc. A strengthened sheath was also introduced for some of the more exposed sections of wiring.
The passive protection includes all interventions to reduce faults due to high current (overload, short cir
cuit).
All system fuses were rated based on the nominal absorbtion of the loads activated at the same time, to
ensure intervention in cases of a clear short circuit.
The introduction of a box containing 4 maxifuses with other fuses connected on the outside means all
the supplies can be protected except for the cable that connects the battery to the starter motor and the
cable that connects the starter motor to the recharging alternator. These cables are therefore protected by a
strengthened supplementary sheath.
In "MAXI" fusebox A:
EFI electronic injection fuse (petrol)
GLOW: plug fuse (diesel)
IGN: ignition switch fuse
J/B2 fuse master supply .
J/B1 fuse master supply
Next to the box.
B: fan fuse (see table)
C: ABS 60A fuse
D: second fan fuse: 40A (JTD)
115961 1998
iFil 30A IJ/B21 BOA
fiGNl 4OA IJTBTI BOA
1910JTD
IGLOWl 60A P7B21 80A
MGNI 40A IJ/Bll 80A
FUSE B
30A engine petrol without air conditioner
40A 1596 with air conditioning, JTD
50A 1998 wth air conditioning
Copyright by Fiat Auto 1
Page 138 of 330

Electrical system
Protection and security devices
Marea-Marea Weekend
2000 range Q
55.
SUPPLEMENTARY FUSEBOX
Many shunt fuses are found under the facia
just above the junction control unit
The fuses are grouped in two special multiple
connectors, one for the front wiring the other
for the facia wiring, according to a pre-set
position and located as shown in the figure:
3A: front wiring
Fuse Protected circuit Amp
- F1 Fuse protecting ignition activated services (15/54) 7.5
- F2 Fuse protecting headlamp washers 20
- F3 Fuse protecting injection and CODE, fan 7.5
- F4 Fuse protecting ABS 10
- F5 Fuse protecting compressor and air conditioner 7.5
- F6 Fuse protecting injection memory and CODE, fan 7.5
3D: facia wiring
Fuse Protected circuit Amp
- F1 Fuse protecting ignition activated services (INT) 7.5
- F2 Fuse protecting foglamps 15
- F3 Fuse protecting rear electric windows 25
- F4 Fuse protecting front electric windows 25
- F5 Fuse protecting sunroof, seats, cigarette lighter 30
- F6 Fuse protecting airbag 10
8 Publication no. 506.763/24
Page 139 of 330
Marea-Marea Weekend Electrical equipment
2000 range (§) Location of components on the car
55.
LOCATION OF RELAYS AND FUSES ON THE VEHICLE (BONNET - Petrol engine types)
Fi998l152B 273 274 i * *
3B-3C Power fusebox
96 Power fuse protecting ABS
98 Headlamp washer intermittent function
122 Engine cooling fan low speed relay
123 Engine cooling fan high speed timer
124 Air condiitoning compressor control relay
129 Power fuse protecting engine coling fan
150 Injection system relay feed
151 Lambda probe control relay for fuel pump
and injectors
152 Fuse protecting injection system
152A Fuse protecting injection system
152B Fuse protecting injection system
273 Fuse protecting automatic transmission
system
274 Fuse protecting automatic transmission
system
276 Starter enablement relay
(••) Versions with air conditioning
(*) With automatic transmission
Copyright by Fiat Auto 9