fuel pressure FIAT MAREA 2001 1.G User Guide

Fuel feed system
Engine Marea- Marea Weekend © ™
2000 range @
10.
The control unit autodiagnostic system checks the signals coming from the sensors and compares them
with the figures allowed:
- signalling faults during starting
- warning light on for 4 seconds indicates test stage
- warning light off after 4 seconds indicates no fault with components that could alter the pollution con­
trol standard figures
- warning light on after 4 seconds indicates fault.
- signalling faults during operation
- warning light on indicates fault
- warning light off indicates no fault with components that could alter the pollution control standard fig­
ures.
- recovery
- from time to time, the control unit defines the type of recovery according to the components which are
faulty
- the recovery parameters are managed by components which are not faulty.
Control of cylinder balancing during idling
According to the signals coming from the sensors, the injection control unit controls the idle speed torque,
altering the injector operating times.
Control of irregular operation
Depending on the signals coming from the sensors, the injection control unit corrects the amount of fuel
to be injected in order to improve driveability and reduce jerking whilst driving.
The correction is achieved through the fuel pressure regulator and by varying the injector operating times.
Control of electrical balance
According to the battery voltage, the injection control unit alters the idle speed, to guarantee a sufficient
current supply from the alternator in situations where the consumers are absorbing a great deal of power.
The variation in the idle speed is achived by regulating the fuel pressure and altering the injector operat­
ing times.
VGT variable geometry turbocharger control (1910 JTD 110 CV)
The injection control unit processes the signal coming from the supercharging sensor, at the various en­
gine operating speeds, and determines the quantity of fuel to be injected, acting on the fuel pressure
regulator and the injector opening times.
In addition, through the solenoid valve, the control unit regulates the geometry of the turbine in order to
ensure optimum performance in all operating conditions.
Turbocharger waste gate valve control (1910 JTD 100 CV)
At the various engine operating speeds, the injection control unit processes the signal coming from the
supercharging sensor and determines the amount of fuel to inject, acting on the fuel pressure regulator
and the injector opening times.
In addition, the control unit controls the opening of the turbocharger waste gate valve, via the solenoid
valve, in order to ensure excellent performance in all operating conditions.
Control of throttle closing when engine is switched off
When the engine is switched off (ignition key in OFF position) the injection control unit closes the throt­
tle valve located on the air intake duct via the special solenoid valve.
This action makes it possible to limit the tiresome shuddering of the engine whilst it is switching off.
6 .i. V!-01-.Cancelftand replaces Print n° 506.763/25

Marea- Marea Weekend 9 ™
2000 range ©
Engine
Fuel feed system
10.
DIAGRAM SHOWING INFORMATION FLOW BETWEN THE INJECTION CONTROL UNIT AND
SENSORS/ACTUATORS
1. Auxiliary fuel pump
2. Variable geometry turbocharger control sole­
noid
3. Climate control compressor
4. Electric EGR valve
5. Rev counter
6. Engine radiator fan
7. Glow plug preheating control unit
8. Potentiometer on accelerator pedal
9. Brake and clutch pedal switches
10. Fuel pressure sensor
11. Intake air flow and temperature sensor (de-
bimeter)
12. Coolant temperature sensor
13. Fuel temperature sensor
14. Pressure relief sensor
15. Timing sensor
16. Rpm sensor
17. Vehicle speed signal
18. Battery
19. Four stage pressure switch
20. Fiat CODE control unit
21. Diagnostic socket
22. Fuel pressure regulator
23. Injectors
24. Throttle valve control solenoid
25. Glow plug preheating warning light
26. Injection system failure warning light
Copyright by Fiat Auto 1

Marea- Marea Weekend 9 ™
2000 range ©) Fuel feed system
Engine
10.
Compents of injection system wiring diagram
1. Vehicle speepd
2. Rev counter
3. Engine radiator fan low speed relay
4. Radiator fan high speed activation relay
5. Potentiometer on accelerator pedal
6. Timing sensor
7. Fuel pressure sensor
8. EGR system modulator solenoid
9. Fuel pressure regulator
10. Glow plug preheating warning light on control panel
11. Injection system failure warning light
12. Air conditioning system relay
13. Coolant temperature sensor
14. Rpm sensor
15. Fuel temperature sensor
16. Diagnostic socket
17. Fiat CODE control unit
18. Four stage pressure switch
19. Injection electronic control unit
20. Pressure relief sensor
21. 7.5A fuse protecting electronic injection system ( + 15 power supply from ignition switch)
22. 7.5A fuse protecting electronic injection system ( + 30 power supply from ignition switch)
23. Main injection system relay
24. 30A fuse protecting injection system
25. Auxiliary fuel pump relay
26. Glow plug preheating control unit
27. Intake air flow and temperature sensor (debimeter)
28. Brake pedal switch
29. Clutch pedal switch
30. Ignition switch
31. Battery
32. Inertia switch
33. Auxiliary fuel pump (submerged in tank)
34. 60A fuse protecting glow plug control unit
35. Cylinder no. 1 glow plug
36. Cylinder no. 2 glow plug
37. Cylinder no. 3 glow plug
38. Cylinder no. 4 glow plug
39. Cylinder no. 1 injector
40. Cylinder no. 2 injector
41. Cylinder no. 3 injector
42. Cylinder no. 4 injector
43. Throttle valve control solenoid
44. Variable geometry turbocharger control solenoid
45. Diesel filter heater relay
Copyright by Fiat Auto 9

Engine Marea- Marea Weekend 9 ™
Fuel feed system 2000 range @
10.
ELECTRONIC INJECTION CONTROL UNIT
The control unit processes signals from the various sensors by applying software algorithms and controls
the actuators accordingly (particularly the injectors and pressure regulator) to achieve the best possible
engine service conditions.
The control unit is "flash E.P.R.O.M." type, i.e. it can be reprogrammed from outside without andy need
to adjust the hardware.
The injection control unit contains a built-in absolute pressure sensor and is connected to the wiring by
means of a 121 pin connector.
Control unit connection identification (PIN-out)
4 5 43 24 6 25 96 106 113 105 119 120 121
1 Earth 25 Not connected
2 Earth 26 Not connected
3 Earth 27 Not connected
4 Actuator power supply 28 Not connected
5 Injector/ECU power supply 29 Not connected
6 Not connected 30 Not connected
7 Not connected 31 Not connected
8 Not connected 32 Not connected
9 Not connected 33 Not connected
10 Not connected 34 Not connected
11 Fiat CODE 35 Not connected
12 Not connected 36 Not connected
13 Injection relay
14 Glow plug control
15 Throttle body solenoid
16 EGR valve
17S VGT solenoid
18 Air conditioner relay
19 Radiator fan high speed relay
20 Radiator fan low speed relay
21 Diagnostic warning light control
22 Glow plug activation control
23 Not connected
24 Auxiliary fuel pump relay
10 Publication no. 506.763/24

Ma tea- Ma tea Weekend !@ ™
2000 range ©
Engine
Fuel feed system
10.
37 Not connected
38 Not connected
39 Not connected
40 Not connected
41 Not connected
42 Not connected
43 Not connected
44 Not connected
45 Not connected
46 Not connected
47 Engine rpm signal output
48 Diagnostic line k
49 Vehicle speed signal input
50 Not connected
51 Activation signal from 4-stage pressure switch
52 Activation signal from 3-stage pressure switch
53 Not connected
54 Not connected
55 Not connected
56 Not connected
57 Not connected
58 Key ON signal
59 Brake switch
60 Air conditioner activation request
61 Clutch switch
62 Glow plug diagnosis
63 Not connected
64 Not connected
65 Not connected
66 Not connected
67 Not connected
68 Not connected
69 Not connected
70 Not connected
71 Not connected
72 Not connected
73 Not connected
74 Not connected
75 Not connected
76 Accelerator pedal 1 earth
77 Accelerator pedal 1 signal
78 Accelerator pedal 1 power supply
79 Accelerator pedal 2 earth
80 Accelerator pedal 2 signal
81 Accelerator pedal 2 power supply
82 Diesel temperature sensor (pin 1)
83 Diesel temperature sensor (pin 2)
84 Coolant temperature sensor (pin 1)
85 Coolant temperature sensor (pin 2)
86 Air flow meter (pin 1)
87 Not connected
88 Air flow meter (pin 3)
89 Air flow meter (pin 5)
90 Fuel pressure sensor (pin 3)
91 Fuel pressure sensor (pin 2)
92 Fuel pressure sensor (pin 1)
93 Turbo pressure sensor (pin 1)
94 Turbo pressure sensor (pin 3)
95 Turbo pressure sensor (pin 2)
96 Not connected
97 Air flow meter (pin 4)
98 Not connected
99 RPM sensor (pin 1)
100 RPM sensor (pin 2)
101 RPM sensor (pin 3)
102 RPM sensor (pin 1)
103 Timing sensor (pin 2)
104 Timing sensor (pin 3)
105 Not connected
106 Not connected
107 Not connected
108 Fuel pressure regulator
109 Fuel pressure regulator
110 Not connected
111 Heater relay control Fuel filter
112 Not connected
113 Not connected
114 Cylinder 4 injector control
115 Not connected
116 Not connected
117 Cylinder 1 and 2 injector power supply
118 Cylinder 3 and 4 injector power supply
119 Cylinder 1 injector control
120 Cylinder 2 injector control
121 Cylinder 3 injector control
Copyright by Fiat Auto 11

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

Engine
Fuel feed system
JTD Marea-Marea Weekend ©
2000 range ©
10.
iH
ft
B I 0 ] I D
[ 0 0 1 1
D
0 1 GLOW PLUG PREHEATING CONTROL
UNIT
The glow plugs are controlled by means of a
preheating control unit under the direct con­
trol of the injection control unit.
The preheating control unit contains a smart
relay that sends a return response (feedback)
to the injection control unit, which is thus in­
formed of faults in the preheating control unit
or glow plug short-circuits to earth.
The figure shows the connectors on the base
of the preheating control unit and the pin-out
1. Earth
2. Injection control unit (pin 22)
3. Power supply from main injection relay
4. Not connected
5. Injection control unit (pin 62)
8. Positive from battery (+30)
G. Glow plugs (only four outputs are used)
ACCELERATOR
PEDAL POTENTIOMETER
Accelerator pedal position is converted to an
electrical voltage signal and send to the injec­
tion control unit by a potentiometer connected
to the accelerator pedal.
Accelerator pedal position is processed to­
gether with rpm information to provide injec­
tion times and pressure.
The sensor consists of a case (1) secured to
the pedal by a flange, which contains an axi-
ally-positioned shaft (2) connected to two
potentiometers (3): main and safety potenti­
ometers.
A coil spring on the shaft ensures the correct
resistance to pressure while a second spring
ensures return upon release.
16 Publication no. 506.763/24

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