manifold FIAT MAREA 2000 1.G User Guide

Engine
Fuel feed system
Marea- Marea Weekend © ™
2000 range ©
10.
FUEL SYSTEM OPERATING DIAGRAM
1. Pressure pump
2. Electrically-controlled EGR valve
3. Flow meter
4. Pressure regulator
5. Fuel filter
6. Instrument panel
7. Glow plug preheating control unit
8. Electronic control unit
9. Injection system relay
10. Return manifold (low pressure)
11. RPM sensor
12. Glow plugs
13. Engine coolant temperature sensor
14. Potentiometer on accelerator pedal
15. Switch on brake pedal
16. Switch on clutch pedal
17. Variable geometry turbocharger
18. Timing sensor
19. Injectors
20. Fuel pressure sensor
21. Variable geometry turbocharger control sole­
noid
22. Auxiliary fuel pump
23. Glow plug preheating warning light
24. System failure warning light
25. Pressure relief sensor
26. Fuel temperature sensor
27. Throttle valve
28. Variable geometry actuator
29. Vacuum tank
30. Exhaust gas heat exchanger
2 Publication no. 506.763/24

Engine
Fuel feed system
10.
1. Pressure rod
2. Pin
3. Nozzle
4. Coil
5. Pilot valve
6. Ball plunger
7. Control area
8. Supply volume
9. Control volume
10. Fuel outlet connector (low pressure)
11. Control port
12. Supply port
13. Electrical connection
14. Fuel input connector (high pressure)
15. Spring
Marea- Marea Weekend 9 ™
2000 range (Q)
INJECTORS
The injectors are fitted to the cylinder head
and are electromagnetic in type. They are
controlled directly by the injection control
unit.
The injectors come with a high-pressure sup­
ply port and a recirculation pipe at environ­
mental pressure; The supply port is connected
to a delivery manifold (rail) with pipes de­
signed to withstand the high service pressures.
The injector can be divided into two parts:
- Actuator/spray made up of a pressure rod
(1), pin (2) and nozzle (3);
- control solenoid made up of coil (4) and
pilot valve (5).
Operation
Injector operation may be divided into three
stages:
1. rest position
Coil (4) is deactivated and plunger (6) is in
closed position to prevent fuel entering the
cylinder: Fc > Fa where Fc is the force gener­
ated by pressure acting on the control area (7)
of pressure rod (1) and Fa is the force due to
the pressure acting on supply volume (8).
2. Start of injection
Coil (4) is excited and causes plunger (6) to
rise. Fuel flows from control volume (9) to
the return manfold to bring about a pressure
drop in control area (7). Simultanteously, line
pressure through supply port (12) exerceses a
force Fa > Fc on supply volume (8) to cause
pin (2) to rise and thus allow fuel into the
cylinders.
3. end of injection
Coil (4) is deactivated and causes plunger (6)
to return to closed position. The resulting bal­
ance of forces makes pin (2) return to rest po­
sition and injection therefore ends.
14 Publication no. 506.763/24

Marea- Marea Weekend 9™
2000 range (§)
4F015XJ03
Engine
Fuel feed system
ijo.
ENGINE COOLANT TEMPERATURE
SENSOR
The sensor is fitted to the thermostat and
measures the temperature of the engine cool­
ant by means of an NTC thermistor with a
negative resistance coefficient.
Because the sensor is made using semicon­
ductor technology, the resistance falls if sen­
sor element temperature rises with increasing
coolant temperature.
Because resistance does not change in linear
manner, it is higher at low temperatures than
at high temperatures for the same temperature
increase.
1. NTC resistance
2. Sensor case
3. Electrical connector
FUEL TEMPERATURE
SENSOR
The sensor is fitted on the return manifold and
measures fuel temperature by means of an
NTC thermistor with a negative resistance co­
efficient.
Refer to the previous description of the cool­
ant temperature sensor for sensor operation.
FUEL PRESSURE SENSOR
The sensor is fitted in the middle of the fuel
delivery manifold (rail) and is responsible for
providing a return signal (feedback) to the
control unit in order to:
- adjust injection pressure;
- regulator injection duration.
Copyright by Fiat Auto 15

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

Engine
Fuel feed system
JTD Marea- Marea Weekend 0
2000 range ©
10.
FUEL SUPPLY CIRCUIT
Operationally-speaking, the fuel supply circuit is divided into a low pressure circuit and a high pressure
circuit.
The low pressure circuit consists of a tank, multifunction valve, auxiliary fuel pump submerged in the tank
and a return manifold.
The high pressure circuit consists of a radialjet pressure pump, delivery manifold and injectors.
1. Fuel tank
2. Submerged fuel pump (auxiliary) with fuel
level gauge control
3. Multifunction valve
4. Pressure pump control pulley
5. Diesel filter cartridge
6. Pressure pump
7. High pressure pipe
8. Delivery manifold (rail)
9. Injectors
10. Fuel recirculation pipe (injector return)
11. Return manifold
12. Pressure regulator
13. Fuel temperature sensor
14. Fuel pressure sensor
15. Diesel heater
16. Fuel temperature sensor
17. Sensor indicating presence of water in fuel
filter
18 Publication no. 506.763/24

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
TZZZZZZZZZZZZZZ*
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
Copyright by Fiat Auto 23

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
Copyright by Fiat Auto r VI-01-Cancels arwl replaces.25

Engine Marea- Marea Weekend IP ™
Fuel feed system 2000 range o
10.
The EGR valve consists of:
- a Pierburg EGR solenoid (1) operated by engine management unit (2)
- a pipe from the exhaust manifold (4) (from which the exhaust gases flow)
- an air-water heat exchanger (3) (that lowers exhaust gas temperature)
- a pipe connected to throttle body (5) to which exhaust gases are admitted
4
Operation
With coolant temperature > 20°C and engine speeds between 800 and 3000 rpm, the engine management
unit controls the EGR solenoid by means of a square wave signal.
Changes in this signal allow the EGR coil to move a plunger and thus modulate the flow of exhaust gas
from the exhaust manifold to the intake manifold; this achieves two results:
- less air is taken in
- combustion temperature is lowered (due to the presence of inert gases), thus reducing the formation of
NOx (nitrogen oxides).
The engine management control unit is constantly informed of recirculation gas quantity via data from the
debimeter. If the intake of a given quantity of air (Qam) is required for a given rpm and the level sent by
the debimeter (Qar) is lower, the difference (Qgr) is the amount of gas recirculated.
Qam - Qar = Qgr
Qam = stored theoretical air quantity
Qar = actual air quantity
Qgr = recirculated gas quantity
An atmospheric pressure signal is used in controlling the EGR valve to detect when the car is being driven at
altitude. The recirculation gas quantity can then be reduced to prevent engine fumes.
28 Publication no. 506.763/24