Page 231
MIXTURE CONTROL UNIT
Removal
1. Thoroughly clean the area around the fuel connec-
tions on the fuel distributor.
2. Disconnect the fuel lines from the fuel distributor.
Disconnect the lines to the injection valves before disconnecting the control pressure line, to avoid damaging
the adjacent lines.
3. Remove the rubber bellows from between the air flow
sensor and the throttle valve housing.
FUEL FILTER (NOTE ARROW IN DIRECTION OF FLOW).
REPLACING THE AIR CLEANER ELEMENT
1. Remove the rubber bellows from between the air flow
sensor and the throttle valve housing.
2. Disconnect the return pipe from the fuel distributor
and the retaining bolts holding the lower section of
the air flow sensor to the air cleaner.
3. Raise the mixture control unit slightly and remove the
cleaner element. Take care not to damage the fuel line.
REMOVING THE RUBBER BELLOWS
4. Undo the retaining bolts, and remove the mixture control unit from the air cleaner.
REMOVING THE AIR CLEANER
4. Remove the cleaner element holder from the bottom
of the air cleaner and clean the air cleaner casing.
5. Fit the cleaner element holder and the new element.
6. Fit the air flow sensor to the air cleaner and connect
the return pipe.
7. Fit the rubber bellows between the air flow sensor and
the throttle valve housing.
240-2))
SAAB
REMOV1NG THE MIXTURE CONTROL UNIT
Page 232
Assembly
1. Make sure that the air cleaner element is in the correct
position and then bolt the mixture control unit to the
air cleaner.
2. Connect the fuel line to the fuel distributor.
3. Fit the rubber bellows between the air flow sensor and
the throttle valve housing.
1
1
i 'TTY
1
Fuel distributor
The fuel distributor must not be dismantled but should
be replaced when faulty.
When separating the fuel distributor from the air flow
sensor, ensure that the control plunger does not fall out.
2
LINE PRESSURE REGULATOR,
1977
3
4
9'1
5 6
UP TO AND INCL. MODEL
1. 0-ring
2. Piston
3. Coil spring
4. Shims
5. Copper washer
6. Screw plug
As from model 1978
The function and appearance of the line pressure regulator are the same as before. However, the shims are now
annular.
The shut-off valve for return fuel from the control pressure circuit is located in the screw plug.
SEPARATING THE FUEL DISTRIBUTOR
FLOW SENSOR
FROM THE AIR
If the control plunger has been removed, it must be thoroughly cleaned in petrol and reassembled. Avoid touching
the plunger with the fingers.
On assembly of the fuel distributor, ensure that the Cring is located in its groove. Tighten the three retaining
bolts to a torque of 3.2-3.8 Nm (2.3-2.7 ft.lb., 32-38
kpcm).
""'
LINE PRESSURE REGULATOR,
1. Piston with 0-ring
2. Spring
3. Shims
4. Screw plug with 0-ring and sealing washer (contains stop
valve for return fuel from control pressure circuit).
Line pressureregulato~
Up to and incl. model 1977
The line pressure regulator is located inside the screw
plug at the return line on the fuel distributor. It consists
of a plunger with O-ring, coil spring, shims, screw plug
and copper washer.
l
240-30
AS FROM MODEL 1978
Adjusting the line pressure
After replacement of the O-ring, the line pressure must
be checked and adjusted if necessary.
The pressure can be increased by fitting additional shims
and decreased by removing shims.
The shims are available in thicknesses of 0.004" and
0.020" (0.1 and 0.5 mm). An 0.004" (0.1 mm) shim produces a change in pressure of 0.07 bar (kp/cm2, 1 psi) and
an 0.020" (0.5 mm) shim, a change in pressure of 0,35
bar (kp/cm2, 5 psi).
A prerequisite for measuring and adjusting the line pres-
SAMS
Page 233
sure is that the fuel pump capacity is correct.
The screw plug should be tightened with a torque of 1315 Nm (9.4-10.8 ft.lb., 130-150 kpcm).
Lever, adjustment arm and sensor plate
Removal
Replacement of stop bracket
1. Separate the mixture control unit from the air cleaner.
2. Remove the lower plastic section of the air flow sensor.
3. Remove the two stop bracket mounting screws and remove the bracket, spring, insulation and connectors.
1. Remove the mixture control unit and remove the lower plastic section and the fuel distributor.
2. Remove the retaining screws and the sensor plate.
3. Remove the circlips from the lever seating and remove,
the shims, rubber seals, spring (on one side) and balls.
4. Remove the counterweight retaining screw and press
out the pivot.
5. Remove the lever with counterweight and adjustment
arm.
Assemble in the reverse order. The order of the parts is
shown in the illustration. Tighten the stop bracket with
the prescribed torque of 4.7-5.3 Nm (3.4-3.8 ft.lb.,
47-53 kpcm). After reassembly, check the insulation between the air flow sensor and the stop bracket by means
of a buzzer or an ohmmeter (not applicable to later model 1977 with a pulse-sensing fuel pump relay). Finally,
adjust the rest position of the sensor plate.
REMOVING THE LEVER
Assembly
1.
2.
STOP BRACKET
1. Stop bracket
2. Stop spring
3. Wire loop
4. Insulation
5. Electric connector (up to early model 1977)
Fit the counterweight to the lever but do not completely tighten the screw.
Place the adjustment arm in the lever in such a way
that the socket head screw on the adjustment arm
is visible.
PLAClNG THE ADJUSTMENT ARM IN THE LEVER
CHECKING THE STOP BRACKET INSULATION
SA.Ml
240-31
Page 234
3.
4.
5.
Grease both bearings with Bosch Ft2v2 silicon
grease.
Place the lever with adjustment arm in the air flow
sensor housing and mount the pivot.
Grease the balls and then fit them together with
the spring, seals, shims and circlips. Fit the spring
to the side where the bearing seating is longest.
Note! The circlips are pressed and should be fitted
with the sharp edge facing outwards.
TIGHTENING
7.
THE COUNTERWEIGHT SCREW
Fit the sensor plate retaining screw and tighten it
with a torque of 5.0-5.5 Nm (3.6-4.0 ft.lb., 50-55
kpcm) and check that the lever can be moved with·
out any resistance being felt .
.
MOUNTING THE CIRCLIP
1. Circlip
2. Shims
3. Seal
4. Spring
5. Ball
6.
Mount the sensor plate in the centring tool and
pla~e the tool and plate in the air venturi. Centre
the lever so that the threaded hole is aligned with
the hole in the sensor plate.
TIGHTENING THE SENSOR PLATE RETAINING SCREW
8.
9.
CENTERING THE LEVER
Tighten the counterweight retaining screw with a
torque of 4.7-5.3 Nm (3.4-3.8 ft.lb., 47-53 kpcm).
240-32
SAAB
Adjust the rest position setting of the sensor plate
by bending the wire loop on the stop bracket underneath the air flow sensor.
Preset the position of the adjustment arm. Using a
depth gauge, measure the distance between the
joint surface of the fuel distributor (across the
screw holes) and the needle bearing roll-er. The dimension should be 0.71"-0.75" (18-19 mm). To
adjust the dimension, turn the mixture adjustment
screw by means of an Allen key.
Page 235
CHECKING THE POSITION OF THE ADJUSTMENT ARM
REMOVING THE INJECTION VALVE
10.
CLEANING OF INJECTION VALVE
11.
Fit the 0-ring and the fuel distributor. The fixing
screws should be tightened to a torque of 3.2-3.8
Nm (2.3-2.7 ft.lb., 32-38 kpcm). Fit the lower
plastic section of the air flow sensor together with
the gasket.
Mount the mixture control unit to the car. Fine adjustment of the basic fuel flow is made by means of
a CO gauge after the engine has been warmed up.
REPLACING INJECTION VALVES
1. Clean the area around the injection valve and its connection.
2. Disconnect the fuel line from the valve. To prevent
the valve turning, hold the hexagon with a spanner.
If an injection valve is found to produce poor atomization of the fuel or to leak under pressure, this may be
the result of particles of dirt having collected around the
valve seating. In some cases, the dirt can be washed away
by flushing the valve in the following manner:
1. Remove the rubber bellows fro-m the air flow sensor.
2. Remove the injection valves from the inlet manifold
and p_lacethem in a container. Do not disconnect the
fuel lines.
3. Switch on -the ignition and disconnect the plug for the
safety circuit at the air flow sensor, allowing the fuel
pump to operate.
4. Raise the lever in the air flow sensor a few times to its
highest position so that the injection'valves will be
flushed by a powerful jet of petrol.
PERFECT ATOMISATION
ACCEPTABLE ATOMISATION
DISCONNECTING THE FUEL LINE
3. Remove the retaining plate.
4. Withdraw the injection valve and pull off the rubber
seal.
Assembly is carried out in the reverse order.
EXAMPLES OF BAD ATOMISATION
240-33
Page 236
Injection valves which have been removed from the car
can also be cleaned by means of an injector tester designed
for diesel equipment. Cleaning with compressed air is not
recommended.
If the fault should still remain, replace the injection valve.
REPLACING THE AUXILIARY AIR-VALVE
1. Pull off the hoses and disconnect the electric terminals.
2. Unscrew the auxiliary air valve.
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KDJE 45
CLEANING BY MEANS OF INJECTOR TESTER
REMOVING THE AUXILIARY
AIR VALVE
REPLACING THE WARM-UP REGULATOR
Assembly is carried out in the reverse order.
1. Clean the area around the warm-up regulator and its
connections.
2. Disconnect the electric terminals and both fuel lines
from the regulator.
3. Dismantle the regulator.
ADJUSTING THE THROTTLE VALVE STOP
1. Check that the throttle valve is central in the housing.
2. Turn the adjustment screw until it just makes contact
with the stop tongue (throttle valve completely closed).
3. Turn the adjustment screw another one-third of a turn
and _lock the screw. A clearance of approx. 0.002"
(0.05 mm) will thus be obtained between the throttle
valve and the housing.
REMOVING THE WARM-UP REGULATOR
Assembly is carried out in the reverse order.
ADJUSTING THE THROTTLE VALVE STOP
240-34
SA.ftll
Page 237
,
ADJUSTMENT OF IDLING SPEED
Toadjust the idling speed, turn the adjustment screwon
"the throttle valve housing by-pass passage.
Adjustment should be made in connection with setting
of CO-value. See adjustment of idling speed.
In the event of failure, check:
The cold start valve
The thermal time switch
The electrical system
2. Measure the control pressure with the engine cold.
kp/cm 2
~l--+-+--+-+-t----ir4*i. -;--;
2,5 L-..J---1---1---+---lf--~t-tf:.~;"'~
:~~~mi:-t--1
~-~\.:;:·;;:::'.~·
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1,5 L-l-~~:·@,l·:·.~...~.:'ifl'~/'
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1,0 l-~~-~,,~---4-f--+-+--t--r,
I
0,5 L-..L....L....L..-L.-.&......L.....L.....&,--',-
0
10
20
30
40
°C
0 438 140 013
S 5200
►
ADJUSTMENT OF IDLING SPEED
kp/cm 2
'
2,5
FAULT-TRACING
In the fault-tracing procedure described below it is assumed that the engine does not have any mechanical
faults and that the ignition system is working properly.
/
2,0
/ I/
1,5
/
V
/
,,/
1,0
V
./
Starting difficulties, cold engine
v.:V
V
,
7
0,5
1. Check the operation of the cold start valve. Remove
the valve and place it in a container. Fuel should be
ejected from the valve when the starter motor is
switched on and when the engine is colder than +113°F
(+45°C). The injection time depends on the temperature.
0
10
20
30
40
0 438 140 020
S.6648
bar
2f,
2P
1,5
1,0
0,5
10
20
30
40
0 438 140 070
oc
S 7197
CONTROL PRESSURE, COLD ENGINE
CHECKING THE COLD START VALVE
240-35
Page 238
3. Check that the auxiliary air valve is open when the engine is cold.
Starting difficulties, warm engine
1. Check the residual pressure in the fuel system after
the engine has been switched off. Excessively low
pressure when the engine is still warm can cause vaporization in the fuel lines.
Check the tightness of the. system.
Check first with the valve open. In the event of leakage,
repeat the test with the valve closed (control pressure
regulator disconnected).
CHECKING THE AUXILIARY
AIR VALVE
4. Check the CO-value (warm engine).
CHECKING THE FUEL PRESSURE
Possible leakage places:
Control pressure regulator
Non-return valve at fuel pump
Cold start valve
Line pressure regulator
Injection valves
External leakage
2. Check the control pressure with the engine warm.
S5202
CHECKING THE CO-VALUE
5. Check for air leakage between the air flow sensor and
the engine.
CHECKING FOR LEAKING AIR
CHECKING THE CONTROL PRESSURE, WARM ENGINE
240-36
sria
.J
l
Page 239
3. Check the CO-value (warm engine).
Poor running during the warming-up period
1. Check the control pressure with the engine cold. Ex•
cessive control pressure during the warming-up period
produces a fuel-to-air ratio which is too lean.
kp/cm2
S5202
CHECKING THE CO-VALUE
it17
1,0 1--t--➔.,,~l-+--t---f-~l-+--+---t
4. Check the rest position of the air flow sensor plate in
the air flow sensor. (The top of the sensor plate should
be level with or slightly lower than (max. 0.02 in., 0.5
mm) the lower edge of the air venturi.) Adjust by
means of the wire loop (~).
0,5 ____
0
....._....._....a......&.....&.....&.--L--'
10
20
30
40
S 5200
0438140013
kp/cm 2
2,5
/
2,0
A-+
s-
,/4f/
1,5
SENSOR PLATE IN REST POSITION
,,/
/~::, V
/2 tr'
V
,,. V
1,0
'/;,
0,5
0
10
20
30
40
0 438 140 020
Q5..._ _ _.__ __.__
20
10
°c
S.6648
_.__ __._ ___,
30
40
oc
S 7197
0 438 140 070
,
CONTROL PRESSURE, COLD ENGINE
r
--1
240-37
Page 240
2. Check the CO-value (warm engine).
4. Check that the warming-up period for the engine is
normal by observing the temperature gauge. An abnormally long warming-up period may be caused by a
faulty thermostat.
S 5202
CHECKING THE CO-VALUE
3. Chee!<that there is no air leaking from between the
air flow sensor andthe engine ..
THERMOSTAT
Poor running, warm engine
1. Check the CO-value (warm engine).
CHECKING FOR LEAKING AIR
S 5202
CHECKING THE CO-VALUE
2. Check the control pressure with the engine warm.
CHECKING THE CONTROL PRESSURE, WARM ENGINE
240-38
SAAB