1978 Citroen CX fuel pressure

Downloaded from www.Manualslib.com manuals search engine ELECTRIC PETROL PUMP
The petrol pump is of the multi roller-vane type, driven by an electric motor which is energized as long as the
ignition is switched on. The rotor, which is fitted eccentrically in the pump housing, has metal roller vanes in
grooves around t.he periphery which, when they are forced outwards under the action of the centrifugal force, ensure
the system-is sealed.
Fuel is drawn into the cavities which,appear in between the roller-vanes, and is then forced into the injection
piping.
The electric motor is submerged’ in fuel. However, there .is no fire risk, since there is never any combustible
mixture in the pump housing. The pump supplies more fuel than the engine consumes under full load, so that
there is always sufficient pressure in the fuel system, whatever the engine speed. Excess fuel flows back to
the tank.
Once the ignition is on, the pump operates at the same time as the starter motor. Once the engine is running, the
airflow sensor energizes the pump.
Thanks to this type of.system, if an injector is faulty ( leaks ) the cylinder in question cannot be flooded if one
has ommitted to switch the ignition off. PETROL FILTER (1) :
A fuel filter, fitted between the pump and the injectors, prevents any impurities from reaching the injectors. PETROL PRESSURE REGULATOR ( 2 ) :
The fuel pressure is maintained constant by the pressure regulator. It comprises a metal housing
is a diaphragm., One side of the dipphragm.is subjected to the fuel under pressure, and the other 2
to the action of a calibrated spring. inside which
side is subjected
When the fuel pressure is in excess of 2 bars ( 29 psi ), the diaphragm lifts and allows fuel to flow back to the
tank.
The pressure provided by the regulator is pre-adjusted at the factory. The chamber on the side of the spring is
connected via a flexible pipe to the inlet manifold. Therefore, the difference between the pressure in the inlet
manifold and that of the fuel is maintained constant.
For any engine load, the drop in pressure at the injectors is therefore the same.

Downloaded from www.Manualslib.com manuals search engine Ill. CHECKING AND ADJUSTING
1
. Energizing the system ..................................................................................................................
2. ,Fuel pump feed ( on operating the starter ) .............................................................................
3. Fuel pump feed ( with engine running ) ...................................................................................
4. Supplementary air control ...........................................................................................................
5. Air-flow sensor ............................................................................................................................
6. Resistors and injectors ................................................................................................... . ........
7. Water temperature sensor ............................................................................................................ .
Dingram 7
8. Air temperature sensor ...............................................................................................................
9. Cold-start injector, and thermal switch ...................................................................................
10. Switch on throttle butterfly spindle ( idling speed function ) ............................................ 11
Switch on throttle butterfly spindle ( maximum power function ) ...................................... 12.
E.C.U: ......................................................................... ..~ ............................................................... . . Diagram 1 I ANNEXE : A
: Checking the ignition .................................................................................. Page 25 B
: Checking the air circuit ................................................................................ Page 26
C : Checking the fuel system and the fuel pressure ........................................... Page 27 D
: Adjusting the idling speed and the exhaust emission .............................. Page 28 NOTE
: On the wiring harness for the injectors, the numbers of the terminals on the E.C.U. terminal board are
visible on the rear section. after having withdrawn the casing secured by the end screw.

Downloaded from www.Manualslib.com manuals search engine ANNEXE : C CHECKING THE FUEL CIRCUIT AND PRESSURE
- Remove the cold-start injector ( 1) and carefully
remove its petrol feed pipe.
- Connect pressure gauge ( 2) onto the cold-start
injector petrol line.
- Fit the cold-start injector zmto the manifold.
- Run the engine at idling speed the petrol pressure
must be regulated to 2 bars ( 29 psi ).
- Disconnect the vticuum pipe ( 3 i from the pressure
regulator the regulated pressure must be 2.5 bars
i 36 l/4 psi ).
If one of the readings is incorrect, check condition
of the flexible vacuum pipe for the pressure
regulator. as well as its aspect. If it is satisfactory
replace the pressure requlotor after making sure
that its VCICUU~ pipe is not blocked totally or
partially at the manifold end.
With the engine stopped, the pressure must
remain stable at 2 bars ( 23 psi ); if not, check
for a leak which could be found at the cold-start
injector, one of the main injectors. or at the level
of the pressure regulator valve diaphragm.

Downloaded from www.Manualslib.com manuals search engine 28 OPERATION N” MA.IE. 144-O : Ch <,c ,ng n,,d nlfjusfiup Ihe u I.-~<~tro,,ir i) <~lrr/mr,ir k’
/,,,.I i,,jrr/io,, S~S,W1, ANNEXE : D - ADJUSTING THE IDLING SPEED AND THE EXHAUST EMISSION
CHECKING CONDITIONS
1.
Checking the idling speed must be carried out
on a clean engine on which the ignition and the
valve clearances are properly adjusted and
fitted with a clean air-filter.
2. Check that the throttle butterfly returns correctly
to its stop.
3. Do not load the alternator by switching an any
of the electrical components, except the iqnition
and the electric cooling fan (s) 4.
Run the engine to bring the oil temperature up
to 70 +o 80’ C ( wait for the electric cooling
fan is) to cut in ). IMPORTANT : Use exclusively (I high tension
tachometer ( do not damage the H.T. lead of
the ignition wiring harness ).
ADJUSTMENT
1. Check that the butterfly is not jammed in position
when it is resting against its stop.
2. Wait for the electric cooling fan (s) to cut in.
3. Use screw ( 1 ) to adjust the idling speed to 850
to 900 rpm.
4. Check the exhaust emission :
The resulting amount of CO - CO2 ( corrected CO
reading 1 must be beI& 4.5 %.
In case this reading cannot be obtained, check the
valve clearances, the ignition, the fuel pressure,
the air-tightness of the aircircuit, and the complete
fuel injection system.
5. On (I vehicle fitted with optional oirtonditioning
switch the compressor on, and adjust the idling
speed from 1000 to 1050
rpm, by adjusting the
screw on the auxiliary box located next to the
electro-vol”e.

Downloaded from www.Manualslib.com manuals search engine TABLE OF FUSES
Supply to
eater unit relay Fuse
Circuits protected
Rating Colour
16 Amps Mauve Heater unit
S toplamps
Accessory terminal
Glove box lightinq
Positive terminal
of battery u + )) 16 Amps Red
E Direction indicators
Ignition Windscreen wipers and washers
switch Horns
Heater relay windinq
Window-winder relay winding
Rheostat -speedometer lighting
Warning lamp panel ( Battery
meter ( Thermal voltmeter-- Brake pad wear warning
lamp - Fuel gauge - Oil pressure warning lamp -
Hydraulic fluid pressure warning lamp-Water temp.
warning lamp )
16 Amps Green Interior lamp
Boot lamp
Cigar-lighter
Clock
Hazard warning lamps
E Voltage regulator
Iqnition Reversing lamps
switch
Rear window heating element
Handbrake warning lamp
Window winder relay 16 Amps White R.H. Switch 0 R.H. window winder
L.H. Switch- L.H. window winder
Lighting
Switch 10 Amps Yellow Ashtray lighting
Cigar lighting
Heater controls lighting
Instrument panel lighting Clock
E Battery meter
Odometers
Sidelamp warning
L.H. sidelamps, front and rear 1 amp
Lighting
Switch 10 Amps Blue R.H. sidelamps, front and rear
Number-plate lamp CIRCUIT DIAGRAM
>
P.T.O.

Downloaded from www.Manualslib.com manuals search engine OPERATION N” MA. 510-00 a : Arrnr~g(,v~ ('I, I 0 / Ih CJ c~lvclric-cil irtslnllc7liori Op. MA. 510-00 a 3
(I.‘1975 -7 1975 J
-
den{
lark
i
6
8
9
0
1
2
3
4
5
6
7
8
9
!l
!2
!3
!4
!5
!6
!7
!8
$0
)l
12
33
34
35
36
37
38
39
41
42
43
44
45
46
47
- DESCRIPTION OF COMPONENTS
Description and Location
‘ront R.H. sidelamp ................................... 74
‘rant R.H. direction indicator .................. 21
1.H. headlamp main beam ................. ..... 78
dipped beam ... .................. 76
3.H. horn 42 .............................................
,.H. horn ....................... ............. ............. 41
,.H. headlamp main beam .......................
77
dipped beam .................... 75
‘rant L.H. sidelamp .........
........................
69
:ront L.H. direction indicator .................. 16
I.T. sensor ............................................ 64
qnition coil ..............................................
61
3lower
motor .........................................
58
;tarter ...................................................... 3
Alternator ..................................................... 5
Xstributor 61 ...................................................
7lectric fan thermal switch .........................
59
Zompressor for horns ................................. 43
Compressor relay ..... .................
.............. 42
3attery ........... ...............................................
1
Joltaqe regulator ....................... ............. 6
Nindscreen washer pump ............. ............... 40
jacket for fault-finding ( diagnosfic) ....... 65
3il pressure switch .... ....................... ... 34
:dle cut-off ........................................... 60
3il temperature switch
35 .............................
Coolant temperature switch ....................... 30
T.D.C. sensor ......................................... 63
Switch for reversing lamps .......................... 8
Relay for window winder ............................. 49
Relay for heater unit 45
................... ..............
Relay for electric fan 58 ..................................
Front R.H. brake unit 28 ...............................
Windscreen wiper motor .............................. 38
Blower motor ................................................ 45
Hydraulic fluid pressure switch ................... 32
Stoplamp switch ........................................... 53
Fuse box ..... .................... 8-44-45-49-69-72
Front L.H. brake unit ........................... ... 26
Front R.H. door lighting switch ... ............
11
R.H. window-winder motor .......................... 51
Glove-box lighting ....................................... 51
Accessory terminal ......................................
5c
Lighting for pneumatic oil gauge .............. 3:
Front L.H. door lighting switch
.................. I[ L.H .
window-winder motor ........................... .47 DESCRIPTION C
No identification
AR
M
LG
TB
co
Front harness
Rear harness
Ynqine harness
dindow-winder harness
Instrument panel harness
Compressor harness jent.
/ark
4”9 50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
iz
67
68
69
70 Description and Location Central interior lamp ............ 10
Cigar-liqhter and lighting
.............. 13-66
Ashtray liqhtinq ...................................
67
Handbrake warning lamp flasher unit
........ 15
Switch for R.H. window-winder
.............. 51
Switch for L.H. window-winder ................ 47
Flasher unit .............................................. 21
Anti-theft switch ......................... 4-8-44-61
Rheostat for fuel qauqe ............................ 25
Switch for interior lamp ... ....................
9
Switch for heated rear window ...................
14
Liqhting for heater controls ..................... 68
Contact for handbrake
............................... 115
R.H. control unit ( liqhtinq )
................... 72
Lighting rheostat for tacho. and speedo.
28
Lighting for intrument panel ................ 68-69
Tachometer
............................................ 64
Battery meter (thermal voltmeter )
.......... 26
Fuel gauge unit
..... ....... ....... ................ 25
Lighting for odometers
....... ......... .......... 28
Clock and lighting ................................ 24-67
Warning lamp for heated rear window
15 .......
Warning lamp for dipped beam 75
_, .................
Warninq lamp for brake pads ................... 27
Warninq lamp for oil temperature
............ 35
Warning lamp for water temperature
.......... 29
Red u STOP 1) warninq lamp
............... 31-33
Warninq lamp for hydraulic fluid presssure 31
Warninq lamp for hazard warning
17
...............
Warninq lamp for sidelamps .................... 70
Warning lamp for direction indicators ...... 23
Warninq lamp for main beam ................. 77
Warning lamp for handbrake
..................... 16
L.H. control unit
Direction indicators and hazard warning lamps .........................................................
19
Horns .......................................................... 41
Windscreen wiper motor ....... .................. 38
Windscreen washer pump .......................... 40
Rear R.H. lamp cluster
Sidelamp ...................................................
73
Stoplamp ....................... .............................. 53
Direction indicator ......................................
19
Reversing lamp ....................... .............
9
Boot lamp ................................................... I2
Heated rear window 14 .....................................
R.H. numberplate lamp ...............................
70
L.H. numberplate lamp ...........
.................... 72
Contact for boot lamp .............................
12
Rear L.H. lamp cluster - Sidelamp
........ 71
,- Stoplamp
.......... 52
- Dir. indicator .. 18
- Rev. lamp ......... 8
IG HARNESSES
Boot harness
Boot-lid harness
Diagnostic harness
Handbrake harness
Flying lead

Downloaded from www.Manualslib.com manuals search engine 2 OPERATION No MA. 510-00 b : Arratzgement of the electrical installation
( jhrl 9/1975 ) TABLE OF FUSES
Supply to
lelay for heater unit
‘ositive battery
erminal (( + 1) Fuse
Circuit protected
Rating Colour
16 Amps Mauve Heater unit
Stoplamps
Accessory terminal
Glove-box lighting
E Direction indicators
Windscreen washers and wipers
Ignition Horns
switch Winding for heater unit relay
Winding for window-winder relay
16 Amps Red Rheostat
- speed0 lighting
Instrument panel : ( Battery meter
( thermal voltmeter ) - Brake pad
wear warning lamp.-Fuel gauge- Oil pressure and temp.
warning lamps - Hydraulic fluid pressure warning lamp-
Coolant temp. warning lamp )
Interior lamp
Boot lamp
Cigar lighter
Clock
16 Amps Green Hazard warning
E Voltage regulator
Ignition Reversing lamps
switch Heated rear window element
Handbrake warning lamp
Relay for window
winder 16 Amps White R.H. switch u,R.H. window-winder
L.H. switch - L.H. window-winder
Lighting switch Ashtray lighting
Lighting for cigar-lighter
Lighting for heat’er control
Clock
10 Amps Yellow
Lighting for Battery meter and
instrument panel
E. Odometers
Sidelamp warning lamp
L.H. sidelamps front and rear
10 Amps Blue R,H. sidelamps front and rear
Number plate lamp Cl RCU I T DI AG RAM

Downloaded from www.Manualslib.com manuals search engine DESCRIPTION OF COMPONENTS
dent.
Ident.
Description ond Location
n ark Description and Location
mark
1
Front R.H sidelamp
74 53
Switch for L.H. window-winder .,, 47
Front R H direction indicator
21 54 Flasher unit
.... 21
2 R.H. headlamp
main beam
78 55 Anti-theft switch
4-a-44-61
dipped beam
76 56 Rheostat for fuel gauqe
,.. 25
4 Horn
41 57
. Switch for interior lamp .,. 10
5 L.H headlamp main beam
.., .., ,.. 77 58
Switch for heated rear window
14
dipped beam”: 75 59 Lighting for heater controls _.. 68
6 Front L H sidelamp
.,. 69 60
Contact for handbrake .._....
16
Front L.H. direction indicator ,.... ._. _._.. 16 61
8 R.H control unit (lighting )
72
H T
sensor connector ,. 64
Lighting rheostat for tacho and speed0
28
9
Ignition coil ,.,
61 62 Lighting for instrument panel 68-69
10
Blower motor 58
Tachometer
.,.
64 11
Starter 3 Battery meter ( thermal voltmeter ) 26 12 Alternator ..I
5
Fuel gauqe unit 25 13
Distributor
61 14 Lighting for odometers _. 28 Electric fan thermal switch 59
Clock and lighting .._.. .,. 24-67
15
Compressor for horns 43 Warning lamp for heated rear window
15 16 Compressor relay 42 Warning lamp for dipped beam
_.. 75 17
Battery 1 Warninq lamp for brake pads 27 18 Voltage regulator . . . . . . . . . . 6 Warning lamp for oil temp. ,,_.. 35
19
Sensor for No 4 cylinder
64 Warning lamp for water temp. ..._.,,, ,,,,. 29 21
Windscreen washer pump ... .. ......
40 Red (( STOP )) warning lamps
31-33 22
Socket for fault-finding (diagnostic) .‘.‘.... 65 Warninq lamp for hydraulic fluid pressure
31 23
Oil pressure switch 34 Warning lamp for hazard warning
17 24 Idle cut-off .._........ 60
Warning lamp for sidelamps
70 25
Oil temperature switch 35 Warning lamp for direction indicators 23 26
Coolant temperature switch 30 Warninq lamp for main beam .‘..... 77 27 ‘I’D f-, SenSOr 63
Warning lamp for handbrake ... .‘........-.. 16 28
Switch for reversinq lamps ... ... ....... 8 63 L H control unit 30
Relay for window -winder ... ... .‘........ 49 Direction indicators and hazard warning 31
Relay for heater unit 45 lamps .,. .,...._ .,. .._ 19
.,. .._.......... 32
Relay for electric fan 58 Horns 41 33
Front R H. brake unit
.._.. 28 Windscreen wiper motor
..,.... 38 34
Windscreen wiper motor
_.............. 38 Windscreen washer pump
.._...... 40 35
Blower motor, ,._..._._....._._..._........ 45 64 Rear R.H. lamp cluster 36
Hydraulic fluid pressure switch _..._......... 32 Sidelamp .._...... 73
37
Stoplamp switch 53 S toplamp
_. _. _. _. _. _. _. 53
.._..............
38
Fuse box 8-44-45-49-69-72 Direction indicator
19
_.. _._.. 39
Front L.H. brake unit
. .._.._............... 26 Reversing lamp 9 41
Front R.H. door interior lamp switch 10
6665 Boot lamp .._. ._. 13
42
R.H. window-winder motor ..- 51 Heated rear window
14 43
Glove&or lightinq .._............ 51 67 R.H. number plate lamp 70
44
Accessory terminal 50 68 _..,......... L.H. number plate lamp
72 45
Lighting for pneumatic oil qauge 33 h9 Contact for boot lamp .._.. .._. .._........ 12 46
Front L.H. door interior lamp switch 9 70 Rear L.H. lamp cluster
- Sidelamp
71 47
L.H. window-winder motor ..: 47 - Stoplamp .._._... 52
48
Central interior lamp
10 - Direct. indic. 18 49
Cigar-lighter and lighting 9-66 - Reversing lamp 8
.._....
50 Ashtray lighting 67 71 Map-reading lamp f Pnl/ns ) .._..._....._.
66
_._......._...................... 51
Handbrake warning lamp flasher unit .._._.._ 15 72-73 Rear R.H. and L.H. door int. lamp switches 52
Switch for R.H. window-winder _..._.. 51 (P(/llgs ) 1 l-12 74-75 Rear R.H. and L.H. int. lamps ( f’nlins ) 1 l-12 DESCRIPTION OF WIRING HARNESSES
No identification PC
Boot lid harness mark
Front harness D <( Diagnostic )) harness AR
Rear harness P.AR Rear interior lamps.harness f I’n//nc )
M Engine harness F
Rear door interior lamp switch harness (Pflj/~.s LG
Window-winder harness MC1 Centre console earth lead( Pall~.~,’ S~/jczr ) TB
Instrument panel harness MC2 Centre console earth lead
co Compressor harness Flying lead UF
Front brake pad wear harness C: Contact harness for reversing lamps
C Boot harness