Page 201
REMOVAL AND INSTALLATION OF NIPPLE ON
FUEL LINE
1. Remove the old nipple as follows:
a. Burn a notch in the fuel line by means of a soldering iron.
2mm
S 5194
POSITION OF FUEL LINE IN TOOL
BURNING OFF THE OLD FUEL LINE
c. Knock down the nipple with a hammer. Hold the
tool against a firm base to prevent upsetting the
nipple.
b. Withdraw the fuel line from the banjo coupling.
(Do not cut the fuel line by means of a knife as
this may damage the banjo coupling and cause
leakage.)
S5193
FITTING THE FUEL LINE
REMOVING THE FUEL LINE
2. Mount the nipple to the fuel line as follows:
a. Cut the fuel line with a knife, cutting off as short
a piece as possible.
b. Secure the fuel line in the fitting tool in such a way
that the protruding length is the same as the length
of the banjo coupling plus 0.08 in. (2 mm).
SAAB
234-3
Page 202
MAKING A FUEL LINE FITTING TOOL
Material:
One pair of pliers
One valve guide (2.0 I engines)
1. Using a hacksaw, saw off the guide to a length of 1.0
in (25 mm).
2. Split the valve guide by means of a hacksaw so that
two cup-shaped halves are obtained.
3. Carefully deburr all edges.
4. Solder the two halves to the pliers with the parting
line running along the centre line of the pliers.
Guide the halves during soldering by inserting an old
valve between them.
0
FUEL LINE FITTING TOOL
234-4
....
.L
Page 203
FUEL INJECTION - THE Cl SYSTEM
The Cl system (Continuous Injection), manufactured by
Bosch, is a mechanical injection system which is based on
the measurement of air flow.
Description
r
I
FUEL INJECTION
ENGINE
1. Fuel filter
2. Fuel distributor
3. Air flow sensor
4. Air cleaner
5. Rubber bellows
6. Warm-up regulator
7. Throttle valve housing
8. Cold start valve
9. Thermo-time switch
10. Injection valve
11. Auxiliary air valve
12. Deceleration valve
u-.
.L
240-1
Page 204
6
1
2
3
FUEL SYSTEM
Line pressure
Line pressure -0.1
c===J
c==J
c==J
c==J
Injection
1. Fuel tank
bar ( 1.4 psi)
pressure
Control pressure
2. Fuel pump
3. Fuel accumulator
4. Fuel filter
5. Fuel distributor
6. Warm-up regulator
7. Cold start valve
8. Injection valves
9. Line pressure regulator (up to and including 1977 model)
10. Line pressure regulator with stop valve (as from 1978 model)
Return, no pressure
)
S6J.t2
Page 205
FUEL TANK, FUEL PUMP
The fuel pump is an electric rotary pump and is mounted
inside the tank. The pump and motor are totally enclosed
and cannot be dismantled for repair. A relief valve is fitted to the fuel pL!mp and is actuated when the pressure is
too high. A check valve in the fuel pump outlet ensures
that the supply pressure in the fuel circuit will not fall to
zero immediately after the pump has stopped.
FUEL ACCUMULATOR
The fuel accumulator is connected to the fuel pipes between the fuel pump and the fuel filter.
Up to and including 1979 model the fuel accumulator is
situated on the left end of the fuel tank.
As from 1980 model the fuel accumulator is positioned
on the under side of the body in front of the fuel tank.
The fuel accumulator has three functions:
1. When the engine stops, the fuel pressure in the system
will drop to approximately 2 bar (kp/cm 2 , 28 psi).
This pressure will be maintained as a result of the fuel
accumulated in the fuel accumulator. This means that
the system will remain pressurized at the "rest pressure"
while the engine is cooling, and this prevents the fuel
from vaporizing, thus facilitating starting when the engine is warm.
2. The accumulator absorbs pressure fluctuations or
surges occurring in the system.
3. When the engine is being started, the fuel accumulator
delays the pressure rise in the fuel system so that the
control plunger in the fuel distributor will have time
to reach its lower position before the injection valve
opens. This prevents too much fuel being injected into
the cylinders.
••
•
THE FUEL ACCUMULATOR
WORKING
THE FUEL ACCUMULATOR
STOPPED
WHEN THE FUEL PUMP IS
••
•
S4470
WHEN THE ENGINE HAS BEEN
IIlIIIllIIlllll Rest pressure
Line pressure
5"1'&
.L
240-3
Page 206
FUEL FILTER
FUEL DISTRIBUTOR
The fuel filter is fitted to the circuit between the fuel accumulator and the fuel distributor. The filter has a paper
element and a nylon strainer.
The fuel distributor distributes the fuel to the injection
valves. The fuel distributor consists of a fuel control unit
and four pressure regulating valves, one for each cylinder.
$4471
...........,
FUEL FILTER
1. Outlet
2. Nylon strainer
3. Paper element
4. Arrow, marking the cross flow direction
5. Rubber cone
6. Inlet
FUEL DISTRIBUTOR
Line pressure
E2ZD
c:rr::::J
c==::J
c==::J
240-4
Line pressure -0.1
Injection pressure
Control pressure
Return, no pressure
SMtB
bar ( 1.4 psi)
Page 207
The skirt of the control plunger is in continuous contact
with the line pressure which also acts on the bottom of
the pressure regulating valve. When the control plunger is
raised by the lever from the air flow sensor plate, four
metering slots (one for each cylinder), which feed the
fuel to the top of the pressure regulating valve, will be
opened. The pressure above the spring-loaded diaphragm
acts on the latter, deflecting it downwards and opening
the outlet to the injection valve. A pressured ifferential
of 0.1 bar (kp/cm2, 1.4 psi) is maintained between the
line pressure and the pressure above the diaphragm. This
constant pressure differential is required to ensure that
the injected quantity of fuel always remains proportional
to the open area of the metering slots and that this is the
same for all four cylinders.
PRESSURE REGULATING
VALVE,
PARTIAL
The fuel distributor also contains a line pressure regulator,
passages for the control pressure, and fuel inlets and outlets.
LINE PRESSURE REGULATOR
The line pressure regulator ensures that the pressure in
the circuit remains constant when the fuel pump is in
operation and also controls the recirculation of fuel to
the tank. When the fuel pump is switched off, the regulator will cause a rapid pressure drop to approximately 2.5
bar (kp/cm 2 , 35 psi), i.e. the rest pressure, which is maintained by means of the O-ring seal and the quantity of
fuel contained in the fuel accumulator. The purpose of
the rest pressure is to prevent the fuel from vaporizing
in the circuit when the engine is warm, which would
otherwise make restarting difficult.
LOAD
S 7372
LINE PRESSURE REGULATOR WHEN THE FUEL PUMP IS
WORKING, UP TO AND INCL. MODEL 1977
PRESSURE REGULATING
VALVE,
FULL LOAD
Line pressure
t::::=:=:::::::::,:==·=:=:=::j
Lin.e pressure
-0.1 bar (1.4 psi)
c:=::::::Jlnjection
pressure
c:::==]Control
pressure
S 7373
LINE PRESSURE REGULATOR WHEN THE ENGINE IS
SWITCHED OFF, UP TO AND INCL. MODEL 1977
Line pressure
i..=::=:=i Return, no pressure
millIIIIIIIIIJ
Rest pressure
SA"8
.L
240-5
Page 208
As from model 1978, the line pressure regulator forms
an integral unit with a shut-off valve to which the return
fuel line from the control pressure regulator is connected.
When the fuel pump is operating, the shut-off valve is actuated mechanically by the control pressure regulator,
whereupon the return fuel from the control pressure regulator, whereupon the return fuel from the control pressure regulator by-passes the shut-off valve to the return
line.
2
LINE PRESSURE REGULATOR,
WARM-UP REGULATOR
When the engine is warm, the warm-up regulator maintains a constant control pressure above the control plunger. When the engine is cold and requires a richer fuel/air
mixture, the control pressure is decreased, allowing the
control plunger in the fuel distributor to rise, and more
fuel to flow to the injection valve.
The warm-up regulator consists of a spring-loaded diaphragm valve.
When the engine is cold, a bi-metal strip reduces the
spring load of the diaphragm. This causes the diaphragm
to open and more fuel to flow through the recirculation
line to the fuel tank, thus lowering the control pressure.
When the engine is running, current flows through the
coil which surrounds the bi-metal strip. As the bi-metal
strip heats up, it will bend away from the spring, and the
pressure on the diaphragm, and thus the control pressure,
will increase. When a warm engine is started, there is no
reduction in the control pressure, as the bi-metal strip is
then affected by the engine temperature.
FUEL PUMP OPERATING
1. Line pressure regulator
2. Shut-off valve
A. Line pressure
8. Return line
C. Control pressure return
When the fuel pump stops running and the line pressure
regulator valve is pressed into its seating, the shut-off
valve is also pressed into its seating, preventing the fuel
system from emptying through the control pressure return.
1
2
4
WARM-UP REGULATOR,
c:===i
c:===i
Return, no pressure
1. Diaphragm
2. Push rod
3. Pressure spring
4. Bi-metal strip
5. Heating coil
S 6136
LINE PRESSURE REGULATOR,
FUEL PUMP IDLE
A. Line pressure
B. Return line
C. Control pressure return
240-6
SAAB
COLD ENGINE
Control pressure
S4477
Page 209
COLD START VALVE
♦
•
The cold start valve is mounted in the throttle valve housing and is connected to the line pressure. The valve, which
is operated by a solenoid coil, is actuated by a thermo-time
switch which is controlled by the engine temperature. The
cold start valve only injects fuel when the starter motor is
running. At temperatures lower than -4°F (-20°C), the
valve can inject fuel for a maximum of 8 seconds (9.5
seconds in later versions). At temperatures higher than
-4°F (-20°C), the injection time is gradually reduced
up to a temperature of approx. 95°F (35°C) at which
temperature the valve is no longer actuated (up to approx.
113°F (45°C) on later versions).
S 4478
WARM-UP REGULATOR,
WARM ENGINE
r:::===tontrol
pressure
'--__,Return,
no pressure
CONTROL PRESSURE REGULATION
Some of the fuel from the fuel distributor is diverted via
a restriction. The control pressure is reduced to 3.7 bar
(kp/cm2, 52.5 psi) in the control pressure regulator or to
0.5-3.7 bar (kp/cm2, 7-52.5 psi) during the warm-up
period. A further restriction is located between the control pressure passageand the top of the control plunger,
and this is designed to eliminate any fluctuations which
may occur in the air flnw c<>ncnr IP.vP.r
COLD START VALVE
INJECTION VALVES
The injection valves are mounted in the inlet manifold at
the cylinder head, and continuously inject atomised fuel
upstream of the inlet valves.
· A spring-loaded valve is contained in each injector and
these open at a fuel pressure of 3.3 bar (kp/cm2, 47 psi).
The valves also contain a small fuel filter.
CONTROL PRESSURE REGULATION
..___
_, Line pressure
[.,,,,.,.,.
,:❖1 Line pressure
INJECTION
VALVE
-0.1 bar (1.4 psi)
C===:::IInjection pressure
[==:::]Control
pressure
SAMS
240-7
Page 210
FUEL BOOSTING SYSTEM, 1979 MODEL
lj
Checking the fuel-boosting function, turbo 1979 model
Turbocharged engines are equipped with a special device
to provide the necessary boost in the fuel supply to the
engine under heavy loads and to improve the cooling of
the engine when running at sustained high speeds.
The device consists of a solenoid valve and a pressure
regulator. The valve and pressure regulator are connected
in parallel with the control pressure regulator in the control pressure system.
1
DEVICE FOR FUEL BOOSTING
1. Speed transmitter
2. Throttle valve switch
3. Solenoid (valve)
4. Pressure regulator
5. Control pressure regulator
6. Fuel distributor
The pressure regulator is preset to a pressure approximately 1 bar lower than that of the control pressure regulator (warm engine), which means that the control pressure
will drop from about 52.6 psi (3.7 bar) to about 38.4 psi
(2. 7 bar) when the solenoid valve opens. This pressure
drop raises the position of the control plunger, which,
in turn, implies a boost in the fuel supply to the engine.
The solenoid valve is energised either by a switch at the
throttle valve which makes the circuit when the throttle
opening is greater than about 144°F (62°C), or by
means of a transmitter which is connected to the speedometer cable and which closes the circuit at speeds in excess of about 80.0 mph ( 130 km/h).
<'· SOLENOID
SWITCH AND PRESSURE REGULATOR
1. Solenoid
2. Pressure regulator
S 5738
VAL VE SWITCH
240-8
SAMI
.!.