1988 BMW 3 SERIES Valve

information on removing and refitting the
intake manifold, refer to Chapter 2A.
The throttle valve inside the throttle body or
carburettor is actuated by the accelerator
cable. When you depress the accelerator
pedal, the throttle plate opens and airflow
through the intake system increases.
On fuel injection systems, a flap inside the
airflow meter opens wider as the airflow
increases. A throttle position switch attached
to the pivot shaft of the flap detects the angle
of the flap (how much it’s open) and converts
this to a voltage signal, which it sends to the
computer.
Fuel system
On carburettor models, the fuel pump
supplies fuel under pressure to the
carburettor. A needle valve in the float
chamber maintains the fuel at a constant
level. A fuel return system channels excess
fuel back to the fuel tank.
On fuel injection models, an electric fuel
pump supplies fuel under constant pressure
to the fuel rail, which distributes fuel to the
injectors. The electric fuel pump is located
inside the fuel tank on later models, or beside
the fuel tank on early models. Early models
also have a transfer pump located in the fuel
tank. The transfer pump acts as an aid to the
larger main pump for delivering the necessary
pressure. A fuel pressure regulator controls
the pressure in the fuel system. The fuel
system also has a fuel pulsation damper
located near the fuel filter. The damper
reduces the pressure pulsations caused by
fuel pump operation, and the opening and
closing of the injectors. The amount of fuel
injected into the intake ports is precisely
controlled by an Electronic Control Unit (ECU
or computer). Some later 5-Series models
have a fuel cooler in the return line.
Electronic control system (fuel
injection system)
Besides altering the injector opening
duration as described above, the electronic
control unit performs a number of other tasks
related to fuel and emissions control. It
accomplishes these tasks by using data
relayed to it by a wide array of information
sensors located throughout the enginecompartment, comparing this information to
its stored map, and altering engine operation
by controlling a number of different actuators.
Since special equipment is required, most
fault diagnosis and repair of the electronic
control system is beyond the scope of the
home mechanic. Additional information and
testing procedures for the emissions system
components (oxygen sensor, coolant
temperature sensor, EVAP system, etc.) is
contained in Chapter 6.
2 Fuel injection system-
depressurising
1
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke or allow open flames or bare light
bulbs near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
1Remove the fuel pump fuse from the main
fuse panel (see illustrations). Note:Consult
your owner’s handbook for the exact location
of the fuel pump fuse, if the information is not
stamped onto the fusebox cover.
2Start the engine, and wait for it to stall.
Switch off the ignition.
3Remove the fuel filler cap to relieve the fuel
tank pressure.
4The fuel system is now depressurised.
Note:Place a rag around fuel lines before
disconnecting, to prevent any residual fuel
from spilling onto the engine(see
illustration).
5Disconnect the battery negative cable
before working on any part of the system.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
3 Fuel pump/fuel pressure-
check
3
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
Carburettor engines
1To test the fuel pump, it will be necessary to
connect a suitable pressure gauge between
the fuel pump outlet, and the carburettor
supply pipe. For this particular test, the fuel
return valve, which is normally connected in
the fuel line from the fuel pump to the
carburettor, mustbe bypassed.
2With the engine running at idle speed, the
pump pressure should be between 0.1 and
0.3 bars.
3Should a pressure gauge not be available, a
simpler (but less accurate) method of testing
the fuel pump is as follows.
4Disconnect the outlet hose from the fuel
pump.
5Disconnect the LT lead from the coil, to
prevent the engine firing, then turn the engine
over on the starter. Well-defined spurts of fuel
should be ejected from the outlet hose.
Fuel injection engines
Note 1:The electric fuel pump is located
inside the fuel tank on later models, or beside
the fuel tank on early models. Early models are
also equipped with a transfer pump located in
the fuel tank. The transfer pump feeds the
main pump, but can’t generate the high
pressure required by the system.
Note 2:The fuel pump relay on Motronic
systems is activated by an earth signal from
the Motronic control unit (ECU). The fuel
pump operates for a few seconds when the
ignition is first switched on, and then
continues to operate only when the engine is
actually running.
Fuel and exhaust systems 4•3
2.4 Be sure to place a rag under and
around any fuel line when disconnecting2.1b Removing the fuel pump fuse on
5-Series models2.1a Removing the fuel pump fuse on
3-Series models
4

Note 3:The following checks assume the fuel
filter is in good condition. If you doubt the
condition of your fuel filter, renew it (see
Chapter 1).
Note 4:In order to get accurate test results, it
is recommended that the fuel pressure be
checked from both the main fuel pump and
transfer pump where applicable.
Fuel pump/transfer pump operational
check
6Bridge the connector terminals that
correspond to the fuel pump relay pins 30 and
87b (L-Jetronic systems) or 30 and 87
(Motronic systems) with a suitable jumper wire
(see illustrations).
7Have an assistant switch the ignition on
while you listen at the fuel tank. You should
hear a whirring sound for a couple of seconds.
Note:This test applies to the transfer pump
also. If there is no whirring sound, there is a
problem in the fuel pump circuit. Check the
fuel pump main fuse and relay first (see
Chapter 12). If the main relay is OK, test the
fuel pump relay.
Fuel system pressure check8Depressurise the fuel system (see Section 2).
9Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation codebefore disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
10Detach the fuel feed line from the fuel rail
on L-Jetronic (see illustration)and early
Motronic systems, or from the fuel filter to the
main fuel line on later Motronic systems.
11Using a tee-piece (three-way fitting), a
short section of high-pressure fuel hose and
clamps, attach a fuel pressure gauge without
disturbing normal fuel flow (see illustration).
Warning: Do not use a plastic tee
fitting for this test. It won’t be
able to withstand the fuel system
pressure.
12Reconnect the battery.
13Bridge the terminals of the fuel pump
relay using a jumper wire.
14Turn the ignition switch on.
15Note the fuel pressure, and compare it
with the pressure listed in this Chapter’s
Specifications.
16If the system fuel pressure is less than
specified:
a) Check the system for fuel leaks. Repair
any leaks found, and recheck the fuel
pressure.b) If there are no leaks, fit a new fuel filter
and recheck the fuel pressure.
c) If the pressure is still low, check the fuel
pump pressure (see below) and the fuel
pressure regulator (see Section 18).
17If the pressure is higher than specified,
check the fuel return line for an obstruction. If
the line is not obstructed, renew the fuel
pressure regulator.
18Turn the ignition off, wait five minutes and
look at the gauge. Compare the reading with
the system hold pressure listed in this
Chapter’s Specifications. If the hold pressure
is less than specified:
a) Check the system for fuel leaks. Repair
any leaks found, and recheck the fuel
pressure.
b) Check the fuel pump pressure (see
below).
c) Check the fuel pressure regulator (see
Section 18).
d) Check the injectors (see Section 20).
Fuel pump pressure check
Warning: For this test, a fuel
pressure gauge with a bleed
valve will be needed, in order to
relieve the high fuel pressure
safely. After the test is completed, the
normal procedure for depressurising will
not work, because the gauge is connected
directly to the fuel pump.
4•4 Fuel and exhaust systems
3.10 Disconnect the fuel feed line
(arrowed) from the fuel rail (L-Jetronic
system shown) . . .3.6d . . . then, use a jumper wire to bridge
the terminals on the connector that
correspond to fuel pump relay pins 30 and
87
3.6c On all 1989 and later models, remove
the four bolts and the protective cover to
gain access to the fuel pump relay and
ECU . . .3.6b On Motronic systems, use a jumper
wire to bridge the terminals on the
connector that correspond to the fuel
pump relay pins 30 and 873.6a On L-Jetronic systems, use a jumper
wire to bridge the terminals on the
connector that correspond to the fuel
pump relay pins 30 and 87b
3.11 . . . and connect the gauge between
the fuel feed line and the fuel rail using a
tee-piece fitting

19Depressurise the fuel system (see Sec-
tion 2).
20Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
21Detach the fuel feed hose from the fuel
rail, and attach a fuel pressure gauge directly
to the hose. Note:If the tee fitting is still
connected to the gauge, be sure to plug the
open end.
22Reconnect the battery.
23Using a jumper wire, bridge the terminals
of the fuel pump relay.
24Turn the ignition switch on to operate the
fuel pump.
25Note the pressure reading on the gauge,
and compare the reading to the fuel pump
pressure listed in this Chapter’s Specifica-
tions.
26If the indicated pressure is less than
specified, inspect the fuel line for leaks
between the pump and gauge. If no leaks are
found, renew the fuel pump.
27Turn the ignition off and wait five minutes.
Note the reading on the gauge, and compare
it to the fuel pump hold pressure listed in this
Chapter’s Specifications. If the hold pressure
is less than specified, check the fuel lines
between the pump and gauge for leaks. If no
leaks are found, renew the fuel pump.
28Remove the jumper wire. Relieve the fuel
pressure by opening the bleed valve on the
gauge and directing the fuel into a suitable
container. Remove the gauge and reconnect
the fuel line.
Transfer pump pressure check
29Depressurise the fuel system (see Sec-
tion 2).
30Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
31Remove the transfer pump access plate
(on some models, it’s located under the rear
seat cushion - on others, it’s located under
the carpet in the luggage compartment).
Disconnect the output hose from the transfer
pump, and connect a fuel pressure gauge to
the outlet pipe.
32Reconnect the battery.33Using a jumper wire, bridge the terminals
of the fuel pump relay.
34Turn the ignition switch on to operate the
fuel pump.
35Note the pressure reading on the gauge,
and compare to the value listed in this
Chapter’s Specifications.
36If the indicated pressure is less than
specified, renew the transfer pump.
Fuel pump relay check
37Switch on the ignition.
38Using a voltmeter, probe the following
terminals from the back of the relay electrical
connector. Check for battery voltage at
terminal 30 (M20 and M30 engines) or
terminal 15 (M10 and M40 engines). Note:If
there is no voltage on models with luggage
compartment-mounted batteries, check for a
faulty fusible link. The 50-amp link is about
6 inches from the battery, in a black wire.
39Turn the ignition off, and disconnect the
relay from the electrical connector. Using a
voltmeter, probe the connector terminals that
correspond to fuel pump relay pins 85 (-) and
86(+) on M20 and M30 engines, or terminal 50
and earth on M10 and M40 engines. Have an
assistant turn the engine over on the starter,
and observe the voltage reading. Battery
voltage should be indicated.
40If there is no voltage, check the fuse(s)
and the wiring circuit for the fuel pump relay. If
the voltage readings are correct, and the fuel
pump only runs with the jumper wire in place,
then renew the relay.
41If the fuel pump still does not run, check
for the proper voltage at the fuel pump
terminals (see Section 4). If necessary, renew
the fuel pump.
4 Fuel pump, transfer pump
and fuel level sender unit-
removal and refitting
2
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
Fuel pump (carburettor engines)
1Disconnect the battery negative cable.
Disconnect both hoses from the pump, and
unscrew and remove the two securing nuts
(see illustration).
2Carefully withdraw the pump from the
cylinder head. If it’s stuck, a slight downward
tap on the thick insulating distance piece with
a piece of wood, should free it.
3Remove the two thin gaskets.
4The fuel pump is a sealed unit, and it is not
possible to renew any of the internal
components. Should an internal fault occur, it
must be renewed complete.5Refitting is a reversal of the removal
procedure, but renew the thin gaskets each
side of the insulating distance piece, and
tighten the fuel pump down evenly to the
torque stated in the Specifications. On no
account alter the thickness of the distance
piece, or the correct operation of the fuel
pump will be upset.
Fuel pump (fuel injection
engines)
Note 1: The electric fuel pump is located
inside the fuel tank on later models with the
Motronic system, or adjacent to the fuel tank
on the L-Jetronic system. The early models
are also equipped with a transfer pump
located in the fuel tank. The transfer pump
feeds the larger main pump, which delivers
the high pressure required for proper fuel
system operation.
Note 2: The fuel level sender unit is located in
the fuel tank with the transfer pump on early
models, or with the main fuel pump on later
models.
6Depressurise the fuel system (see Sec-
tion 2) and remove the fuel tank filler cap to
relieve pressure in the tank.
7Disconnect the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Externally-mounted fuel pump
8Raise and support the vehicle.
9Remove the two rubber boots that protect
the fuel pump connectors, and disconnect the
wires from the pump (see illustration).
10Using hose clamps, pinch shut the fuel
hoses on each side of the fuel pump. If you
don’t have any hose clamps, wrap the hoses
with rags, and clamp them shut with self-
locking pliers, tightened just enough to
prevent fuel from flowing out.
11Disconnect the hoses from the pump.
12Remove the fuel pump mounting screws
Fuel and exhaust systems 4•5
4.1 Fuel pump on carburettor engines
4

6Unscrew the four nuts retaining the air
cleaner to the carburettor, and remove the
metal ring (see illustrations).
7Unscrew the nut from the mounting bracket
(see illustration).
8Lift the air cleaner from the carburettor, and
disconnect the crankcase ventilation hose
(see illustration). If necessary, prise the
sealing ring from the bottom of the air cleaner.
9Refitting is a reversal of removal, but align
the arrow on the cover with the arrow on the
inlet tube (see illustration).
Fuel injection engines
10Detach the air intake duct from the front
side of the air cleaner.11Detach the duct between the air cleaner
and the throttle body.
12Remove the air filter (see Chapter 1).
13Unplug the electrical connector from the
airflow meter (see Section 12).
14Remove the air cleaner mounting bolts
(see illustration)and lift the air cleaner
assembly from the engine compartment.
15Refitting is the reverse of removal. Ensure
that all ducts are securely refitted, or air leaks
will result.
9 Accelerator cable- check,
adjustment and renewal
1
Check
1Separate the air intake duct from the
throttle body (fuel injection models) or remove
the air cleaner (carburettor models).
2Have an assistant depress the accelerator
pedal to the floor while you watch the throttle
valve. It should move to the fully-open
position.
3Release the accelerator pedal, and make
sure the throttle valve returns smoothly to the
fully-closed position. The throttle valve should
not contact the body at any time during its
movement; if it does, the unit must be renewed.
Adjustment
4Warm the engine to normal operating
temperature, then switch it off. Depress theaccelerator pedal to the floor twice, then
check the cable free play at the
carburettor/throttle body. Compare it to the
value listed in this Chapter’s Specifications.
5If the free play isn’t as specified, adjust it by
turning the adjustment nut (see illustration).
6Have an assistant help you verify the
throttle valve is fully open when the
accelerator pedal is depressed to the floor.
Renewal
Note:The following paragraphs describe the
procedure for fuel injection engines - the
procedure is similar on carburettor engines
7Disconnect the battery negative cable.
Fuel and exhaust systems 4•9
8.6b . . . and remove the metal ring8.6a Unscrew the four air cleaner-to-
carburettor nuts . . .8.4 Air cleaner inlet duct (1) and warm-air
hose (2)
9.5 To adjust the accelerator cable free
play, hold nut B stationary and turn nut A
(fuel injection engine shown)8.14 Remove the two nuts (arrowed) from
the air cleaner assembly (Motronic system
shown), and lift it off its mountings
8.8 Disconnecting the crankcase
ventilation hose from the air cleaner8.7 Air cleaner mounting bracket nut
(arrowed)8.9 Align the air cleaner cover arrows
when refitting
4

Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code before
disconnecting the battery. Refer to the
information on page 0-7 at the front of this
manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
8Loosen the cable adjuster locknuts, and
detach the cable from its support bracket
located on the intake manifold (see
illustration).
9Pinch the plastic retainer with a pair of
needle-nose pliers, and push it out of the
bracket (see illustration).10Pull the cable down through the slot and
away from the bracket (see illustrations).
11Working from underneath the driver’s side
of the facia, reach up and detach the
accelerator cable from the top of the pedal.
12Pull the cable through the bulkhead, from
the engine compartment side.
13Refitting is the reverse of removal. Adjust
the cable as described earlier.
10 Carburettor-
general information
1Early models are fitted with a Solex 2B4
carburettor, and later models are fitted with a
Solex 2BE carburettor. Both carburettors are
of downdraught, two-stage type. The first
stage is operated mechanically by the
accelerator pedal, and the second stage by
vacuum control.
2Each stage has its own float chamber, float
assembly and needle valve, designed to
reduce the effects of braking and centrifugal
forces.
3On the 2B4 version, the primary stage
choke valve is operated by an automatic
choke (a bi-metal spring which is electrically
heated) during the warm-up period. Warm-up
enrichment is also provided by a coolant-
operated thermal valve and air temperature-
controlled flow valve.
4On the 2BE version, an electronic controlunit is used to automatically adjust the
carburettor settings during warm-up and
normal temperature operation. The control
unit is located beneath the right-hand side of
the facia.
11 Carburettor-
removal and refitting
2
Removal
1Remove the air cleaner as described in
Section 8.
2Disconnect the accelerator cable from the
carburettor with reference to Section 9.
3On automatic transmission models,
disconnect the kickdown cable.
4Disconnect the wiring from the carburettor,
noting the location of each wire.
5Remove the screw, and disconnect the
earth cable from the throttle positioner
bracket (see illustration).
6Disconnect the vacuum hoses, noting that
the hose with the white tracer is located on
the white plastic ‘T’ piece, and the distributor
vacuum hoses are located on the side of the
carburettor (see illustration).
7On the 2B4 carburettor, disconnect and
plug the coolant hoses from the TM (thermal
starter) valve.
8Disconnect the fuel supply hose (see
illustration).
4•10 Fuel and exhaust systems
11.8 Disconnect the fuel supply hose
(arrowed)11.6 Note the locations of the carburettor
vacuum hoses (arrowed) before
disconnecting them11.5 Remove the screw, and disconnect
the carburettor earth cable (arrowed)
9.10b After the cable is off the throttle
valve assembly, remove the plastic
retainer from the cable
9.10a Rotate the throttle valve and remove
the cable end from the slotted portion of
the valve9.9 Pinch the plastic retainer, and push it
through the bracket recess on the throttle
valve9.8 Push the rubber grommet from the
rear, and separate the cable from the
bracket

9Unscrew the four bolts, and lift the
carburettor from the insulating flange on the
intake manifold (see illustration).
10If necessary, unscrew the nuts and
remove the insulating flange from the intake
manifold (see illustration).
Refitting
11Refitting is a reversal of removal, but
clean the mating faces thoroughly. The
insulating flange may be re-used, if it’s in
good condition. Adjust the accelerator cable
with reference to Section 9, and the kickdown
cable (where applicable) with reference to
Chapter 7B.
12 Carburettor-
cleaning and adjustment
4
Note:This Section describes the procedure
for the 2B4 carburettor. The procedure for the
2BE carburettor is similar.
Cleaning
1Obtain a complete set of gaskets and seals
for the carburettor.
2Wash clean the exterior surfaces of the
carburettor.3Using a screwdriver, prise the accelerator
pump linkage from the primary throttle arm
(see illustration).
4Unscrew the bolts securing the cover to the
main body. An Allen key is necessary to
remove the centre bolt (see illustration).
5Prise the link from the choke valve plastic
lever (see illustration).
6Lift the cover from the main body, and
remove the gasket (see illustrations).
7Remove the screw securing the throttle
positioner bracket to the throttle housing (see
illustration).
8Disconnect the vacuum unit pullrod from
the secondary throttle lever (see illustration).
Fuel and exhaust systems 4•11
12.3 Using a screwdriver to disconnect
the accelerator pump linkage (arrowed)11.10 Carburettor insulating flange on the
intake manifold can be removed if
necessary11.9 Unscrew the four bolts (arrowed) and
lift the carburettor from the intake
manifold
12.7 Throttle positioner bracket-to-throttle
housing screw (arrowed)12.6c View of the carburettor main body
with the cover removed12.6b View of the underside of the cover
12.6a Lifting the cover from the
carburettor main body12.5 Prise the link (arrowed) from the
choke valve plastic lever12.4 Using an Allen key to remove the
carburettor cover centre bolt
4

12.13e The jet positions in the cover
(arrowed)
4•12 Fuel and exhaust systems
12.13d Secondary bypass air jet (1), TM air
jet (2), and air correction jet (3)12.13c Secondary main jet (left) and TM
fuel jet (right) tightened in the cover
12.13b Secondary main jet (1) and TM
(thermal starter) fuel jet (2)12.13a Unscrew the bypass jet from the
secondary float chamber12.12b . . . then lift out the needle valves,
keeping all components identified side for
side
12.12a Tap out the float pivot pins, and
remove the floats . . .12.11a Throttle housing removed from the
carburettor12.11b Underside of the main body with
throttle housing removed - note gasket
12.10 Primary throttle lever securing nut -
if removed, take care not to disturb the
return spring12.9 Throttle housing-to-main body
securing screws (arrowed)12.8 Disconnecting the vacuum unit
pullrod

9Remove the screws securing the throttle
housing to the main body (see illustration).
10Prise out the intermediate throttle link. If
this proves difficult, unscrew the nut and
disconnect the lever from the primary throttle
spindle, taking care not to disturb the return
spring (see illustration).
11Separate the throttle housing from the
main body, and remove the gasket (see
illustrations).
12With the cover inverted, tap out the float
pivot pins, remove the floats, and lift out the
two needle valves - keeping all the
components identified side for side (see
illustrations).
13Unscrew the bypass fuel jet from the
secondary float chamber, then similarly
remove the jets from the cover - keeping them
all identified for location (see illustrations).
14Clean all the components, and blow all
the internal channels clear using low air
pressure.
15Reassembly is a reversal of dismantling,
but note the following points:
a) Fit the new gaskets and seals supplied in
the repair kit.
b) Before refitting the cover, check that the
choke linkage arm is correctly located in
the lever (see illustration).
c) Check and if necessary adjust the float
settings. Invert the cover, and check thedistance from the contact face (without
gasket) to the top of the float, making sure
that the needle valve spring-tensioned
ball is not depressed (see illustration).
Note that the dimension is different for
the primary and secondary floats (see
Specifications). If adjustment is
necessary, bend the float arm as required.
d) Make sure that the seal is fitted to the top
of the accelerator pump (see
illustration).
Adjustment
Note:Idle speed and mixture adjustments are
covered in Chapter 1.
Automatic choke (2B4)16Check that the automatic choke cover
and housing alignment marks are clearly
visible; if not, make new marks.
17Remove the three screws and withdraw
the metal ring (see illustration).
18Remove the plastic cover, at the same
time disengaging the bi-metal spring from the
control lever (see illustration).
19Fit a rubber band to the bottom of the
control lever. Push the pulldown lever to the
right and use a 4.2 mm diameter drill to check
the distance between the lower edge of the
choke valve and the wall of the carburettor(see illustration). Alternatively apply vacuum
to the pulldown unit to move the lever.
20If adjustment is necessary, turn the screw
on the end of the pulldown unit (see
illustration).
21Refit the cover in reverse order, making
sure that the alignment marks are in line.
Throttle positioner (2B4)
22With the throttle in the idle position, check
that the length of the spring on the throttle
positioner is 23.0 ± 1.0 mm. If not, adjust the
nut as required.
23With no vacuum applied (engine stopped)
check that the control travel, measured
between the stop screw and lever, is 5.0 ±
0.5 mm. If necessary, loosen the locknut and
turn the diaphragm rod as required. Tighten
the locknut on completion.
Fuel and exhaust systems 4•13
12.15b To check the float level, measure
the distance between the contact face and
the top of the float12.15a Choke linkage arm located in the
automatic choke lever
12.20 If adjustment is necessary, turn the
screw (arrowed) on the end of the
pulldown unit
12.19 Fit a rubber band (2) to the bottom
of the control lever, then push the
pulldown lever to the right, and use a
4.2 mm diameter drill (1) to check the
distance between the lower edge of the
choke valve and the wall of the carburettor
12.17 Remove the three screws and
withdraw the metal ring
12.15c Accelerator pump seal (arrowed)
12.18 Remove the automatic choke cover,
at the same time disengaging the bi-metal
spring from the control lever
4