2000 FIAT MAREA intake

Marea- Marea Weekend 9"°
2000 range ©
Engine
Fuel feed system
10.
TIMING SENSOR
The Hall effect sensor is fitted to the cylinder head and faces the camshaft pulley.
An opening on the pulley allows the timing sensor to detect the engine timing position and indicate it to
the injection control unit.
The injection control unit uses the timing sensor signal to detect TDC at the end of compression.
Operation
A semi-condulator layer, through which a current passes, immersed in a magnetic field (lines of force per­
pendicular to the direction of the current), produces a difference in power, known as Hall voltage.
If the intensity of the current remains constant, the voltage produced only depends on the intensity of the
magnetic field. The intensity of the field can simply be altered periodically to produce a modulated electri­
cal signal. Signal frequency is proportional to the speed with which the magnetic field changes.
To achieve this change, the sensor is crossed by a metal ring (inner part of the pulley) with an opening.
When it moves, the metal part of the ring covers the sensor to magnetic field and the output signal is
therefore low; Conversely, the sensor generates a high signal at the opening when the magnetic field is
present.
This signal, together with the rpm and TDC signals, allows the injection control unit to identify piston po­
sition and determine injection point.
AIR FLOW METER
(DEBIMETER)
The debimeter is located on the air intake
sleeve and is hot film type.
The debimeter contains an intake air tem­
perature sensor.
Operation
The principle of operation is based on a
heated membrane fitted into a measurement
channel through which engine intake air
flows.
The hot film membrane is maintained at a
constant temperature (about 120 °C higher
than incoming air) by the heater coil.
The mass of air flowing through the measure­
ment channel tends to take heat from the
membrane. To keep the membrane at constant
temperature, a certain current level must flow
through the resistance.
Because this current is proportional to the
mass of air that flows to the engine, it can be
measured with a Wheatstone bridge and the
resulting signal is sent to the injection control
unit.
1. Covers
2. Electronic card
3. Sensor
4. Mounting plate
5. Mount
6. o-ring
7. Temperature sensor
Copyright by Fiat Auto 13

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

Marea- Marea Weekend 9 ™
2000 range (Q)
4F019XJ01
1. Impeller
2. Volumes
3. Intake port
4. Outlet port
5. Rollers
6. Outer race
7. Pressure relief valve
4F019XJ02
Engine
Fuel feed system
10.
SUBMERGED FUEL PUMP ASSEMBLY
(AUXILIARY) AND LEVEL GAUGE CON­
TROL
The assembly consists mainly of:
- a roller-type fuel pump;
- a fuel level gauge;
- a fuel filter
The submerged fuel pump is volumetric type
with rollers and a motor with brushes and
permanent magnet excitation.
Impeller (1) is driven by the electric motor to
turn and create volumes (2) that move from
intake port (3) to outlet port (4).
These volumes are delimited by rollers (5) that
adhere to outer race(6) as the motor turns.
The pump is fitted with two valves: a check
valve to prevent the fuel circuit emptying
(with the pump off); a second pressure relief
valve (7) that short-circuits the outlet to the
inlet when pressures exceed 5 bars.
FUEL FILTER
The fuel filter is located in the engine bay.
The filter is cartridge type with a filter element
(1) made up of a pack of paper discs with a
filtering area of some 5300 cm 2 and a filter
gauge of 4 - 5 microns.
The filter is equipped with a fuel preheating
device (2) controlled by the engine control
unit via a relay.
The control unit activates or deactivates the
diesel filter on the basis of a diesel tempera­
ture signal sent by sensor (3) on the filter.
A plug (4) screwed to the base of the fuel
filter cartridge is used to drai off the water.
The plug incorporates a sensor for the detec­
tion of water in the diesel filter connected to a
warning light on the instrument panel.
1. Filter cartridge
2. Diesel preheating device
3. Diesel temperature sensor
4. Water drain plug with sensor to detect
presence of water in diesel filter
Copyright by Fiat Auto 19

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

Marea- Marea Weekend <§l ™
2000 range ©
Engine
Fuel feed system
TZZZZZZZZZZZZZZZZZZb
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10.
MULTIFUNCTION VALVE
The multifunction valve is located on the fuel
tank and performs the following functions:
- tank pressurisation
- ventilation
- seal if the car rolls over
Tank pressurisation
Tank pressurisation is maintained at a level be­
tween 55 and 75 mbars by means of a valve
mounted on a sealing rim.
The valve is supported by a steel plate and held in place by a spring.
When tank pressure exceeds a specified level, it overcomes spring resistance and allows the valve to rise
so that vapours can flow out.
When the pressure returns to within specified limits, the valve closes again
Ventilation
Under certain car service conditions, a vacuum may build up in the tank due to the effect of:
- heat changes;
- fuel consumption
in this case, the valve's function is to make up pressure inside the tank by letting air into the tank.
If this function is not performed correctly, the car may judder or stall due to difficulties in supplying the
pump.
Seal if the car rolls over
The roll-over function prevents fuel emerging from the tank if the car rolls over or tilts to a great extent.
During normal car operation (bends, acceleration, braking etc.), the fuel slops about and may emerge.
The highly-sensitive roll-over valve prevents this happening.
DELIVERY MANIFOLD (RAIL)
The delivery manifold (rail) is fitted to the cylinder head on the intake side.
Its volume damps fuel pressure fluctuations due mainly to:
- operation of the pressure pump;
- injector opening.
A fuel pressure sensor is fitted in the middle of the delivery manifold.
Hydraulic connections (high pressure) are via special steel pipes.
Copyright by Fiat Auto 21

Marea-Marea Weekend 9 Engine
2000 range ©) Fuel feed system
10.
AIR INTAKE CIRCUIT
The air intake circuit is turbocharged by means of of a GARRET variable geometry turbocharger and an
intercooler.
The turbocharger is low inertia type. Its design is based on a new principle of turbocharging whereby the
turbocharger aims to increase torque within the range of most frequent use (e.g. at low speeds).
After passing through the filter (1), intake air is compressed by the exhaust gas-drive turbocharger (4),
cooled by intercooler (5) and sent to throttle body (6) and the intake manifold from where it is distributed
to the cylinders.
Air intake circuit diagram
4F023XJ01
1. Intake vent
2. Air filter
3. Intake airflow meter (debimeter)
4. Variable geometry turbocharger
5. Air-air intercooler
A. To turbocharger
B. To intake manifold
6. Throttle body
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Engine Marea- Marea Weekend 9*nD
Fuel feed system 2000 range (§)
10.
THROTTLE BODY
To reduce engine noise during shut-down, a throttle has been added to the intake port with the aim of
closing off the air flow to the cylinders.
Throttle valve opening or closure is controlled by an engine control unit (5) that manages a control ac­
tuator (3) on throttle body (4) via solenoid (2).
Operation
When the engine is off, the throttle is open because no vacuum is present.
When the engine is running, the throttle is open because the Pierburg solenoid is not activated and pre­
vents the vacuum reaching the pneumatic actuator.
A vacuum builds up in the tank during engine operation.
During engine shut-down (when the ignition key is turned OFF), the control unit keeps the actuator sup­
ply relay activated for a further 4 or 5 seconds and simultaneously earths the Pierburg valve. The Pierburg
valve opens to send the vacuum that has built up in the vacuum tank to the pneumatic actuator, which
closes the throttle to cut off the flow of air to the cylinders.
4F024XJ01
1. Vacuum tank;
2. Pierburg solenoid controlling throttle body
actuator;
3. Pneumatic actuator on throttle body
4. Throttle body
5. Engine control unit
6. Vacuum pump
24 Publication no. 506.763/24

Marea- Marea Weekend 9
2000 range ©
Engine
Fuel feed system
10.
TURBOCHARGER (1910 JTD 110 CV)
The turbocharger used in the application of the
EURO 3 standards in the variable geometry
type connected to the exhaust manifold.
The turbocharger is controlled by the engine
management control unit via a duty-cycle so­
lenoid valve.
The increased volumetric output for the engine
is achieved, in the case of variable geometry
compressors, through the use of:
- a centrifugal compressor (1)
- a turbine (2)
- a series of moving vanes (3)
- a pneumatic actuator (4) controlling the
moving vanes.
- asolenoid valve (5) controlling the actuator
The variable geometry turbocharger makes it
possible to:
- increase the speed of the exhaust gases in
the turbine at low engine speeds
- slow down the speed of the exhaust gases
in the turbine at high speeds.
The control of the speed (kinetic energy) of
the exhaust gases makes it possible to pro­
duce increased engine torque at low speeds
and greater maximum power at high speeds.
Operation at low rotation speeds
When the engine is operating at low speeds,
the exhaust gases possses little kinetic energy:
under these circumstances a conventional tur­
bine would rotate slowly, supplying a limited
supercharging pressure.
On the other hand, in the variable geometry
turbine (1), the moving vanes are in the
maximum closure position and the small pas­
sage sections between the vanes increase the
speed (C) of the intake gases.
Increased intake speeds lead to increased pe­
ripheral speeds (U) of the turbine and, conse­
quently, the compressor.
The speed of the gases inside the impeller is
indicated by the vector (W).
1. Turbine
2. Moving vanes
3. Pneumatic actuator
4. Rotary seal
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