Ford Orion. Manual - part 34

high-pressure air line must not be applied to
the accelerator pump discharge assembly or
the pump supply valve, as they each contain a
rubber Vernay valve, and these can easily be
damaged under high pressure. Never use a
piece of wire for cleaning purposes.
17 Examine all of the carburettor
components for signs of damage or wear,
paying particular attention to the diaphragms,
throttle spindle and plates, needle valve and
mixture screw; the power valve jet is adjacent
to the primary main jet. Renew all
diaphragms, sealing washers and gaskets as
a matter of course.

Reassembly

18 Refit the throttle housing to the
carburettor main body (fitting a new gasket),
and secure with its retaining screws.
19 Refit the fuel mixture screw. Make an
initial adjustment by screwing it fully in (but do
not overtighten or screw it onto its seat), then
unscrew it two full turns.
20 Where fitted, reassemble the throttle
kicker, ensuring that its diaphragm lies flat,
and that the relative position of the operating
link to the kicker cover is correct.
21 Fit the power valve, ensuring that its
diaphragm lies flat and the vacuum gallery
aligns with the diaphragm and housing.
22 Refit the accelerator pump. Take care not
damage the valve as it is inserted, and check
that the O-ring seal is correctly located on the
end of the valve. Check that the valve is not
trapped by the spring.
23 Refit the accelerator pump discharge jet.
Take care not to damage the valve and/or the
O-ring seal, and ensure that they are correctly
located.
24 Commence reassembly of the upper body
by inserting the emulsion tubes and the air
correction jets into their respective ports (as
noted during removal).
25 Screw the anti-dieselling solenoid into
position. Ensure that the aluminium washer is
fitted, and take care not to overtighten the
valve.
26 Refit the needle valve and the float, and

adjust the float setting as described in Sec-
tion 14.
27 Refit the choke control mechanism, and
secure with its three retaining screws.
28 Locate a new gasket onto the mating
face, then refit the carburettor upper body to
the main body. As they are reassembled, take

care not to snag the float on the carburettor
main body. Fit and tighten the retaining
screws to secure.
29 With the carburettor reassembled, refit it
to the vehicle and adjust it as described in
Chapter 1. Where applicable, check and
adjust the throttle kicker setting.

18 Carburettor (Weber TLD) -

description

This carburettor incorporates many of the

features of the TLDM type fitted to 1.3 litre
HCS engines. The main differences are that
the secondary venturi (barrel) is vacuum-
operated, and that a coolant-heated
automatic choke control system is fitted (see
illustrations).

The choke system is fully automatic. When

the engine is cold, the bi-metal spring which
controls the position of the choke plate is fully
wound up, and holds the plate closed. As the
engine warms up, the bi-metal spring is
heated by the coolant and begins to unwind,

Fuel and exhaust systems – carburettor engines  4A•11

18.1A  Exploded view of the Weber TLD type carburettor as fitted to the 1.6 litre engine

18.1C  General view of the Weber TLD type

carburettor

A  Automatic choke housing
B  Secondary barrel vacuum diaphragm

18.1B  General view of the Weber TLD type

carburettor

A  Throttle kicker unit (not fitted on all models)
B  Accelerator pump
C  Power valve
D  Choke diaphragm (automatic choke)

A   Emulsion tubes
B   Air correction jets
C   Automatic choke unit
D   Choke pull-down

diaphragm

E   Main jets

F   Secondary barrel

diaphragm

G   Power valve diaphragm
H   Accelerator pump

diaphragm

J   Mixture screw
L   Needle valve
M   Anti dieselling (fuel cut-off)

solenoid

N   Fuel supply filter

4A

thereby progressively opening the choke
plate. A vacuum-operated pull-down
mechanism controls the choke plate under
certain operating conditions, and an internal
fast idle system is incorporated.

The carburettors used on cars with CTX

automatic transmission have a throttle
position sensor and throttle plate (idle speed)
control motor for additional control of certain
engine functions. A similar system is used on
cars equipped with air conditioning.

19 Carburettor (Weber TLD) -

fast idle speed adjustment

4

Note:  Before carrying out any carburettor
adjustments, ensure that the spark plug gaps
are set as specified, and that all electrical and
vacuum connections are secure. To carry out
checks and adjustments, an accurate
tachometer and an exhaust gas analyser (CO
meter) will be required.
1 Check that the idle speed and mixture
settings are as specified (as described in
Chapter 1). These must be correct before
checking/adjusting the fast idle speed.
2 Switch the engine off, then remove the air
cleaner as described in Section 2.
3 With the engine at its normal operating
temperature and a tachometer connected in
accordance with its manufacturer’s
manuals, hold the throttle linkage partly
open, then close the choke plate until the fast
idle adjustment screw aligns with the 4th step
on the fast idle cam (see illustration).
Release the throttle linkage so that the fast
idle speed adjustment screw rests on the
cam. Release the choke plate. The linkage will
hold it in the fast idle speed setting position,
as long as the accelerator pedal is not
depressed.
4 Without touching the accelerator pedal,
start the engine and record the fast idle speed
achieved. If adjustment is required, turn the
fast idle speed adjuster screw until the
specified fast idle speed is obtained.
5 When the throttle linkage is opened, the

choke plate should return to its fully-open
position. If this does not happen, either the
engine is not at its normal operating
temperature, or the automatic choke
mechanism is faulty.
6 Switch off the engine and disconnect the
tachometer. Refit the air cleaner.

20 Needle valve and float (Weber

TLD carburettor) - removal,
refitting and adjustment

4

1 Refer to Section 14 and proceed as
described, noting the following difference.
2 In paragraph 4, ignore the manual to
detach the choke cable (an automatic choke
is fitted to the TLD type carburettor). Instead,
clamp the coolant supply and return hoses
which lead to the automatic choke unit to
minimise coolant loss, then ensure that the
cooling system is not pressurised (see
Chapter 3). Identify then detach both of the
coolant hoses at the automatic choke housing
(see illustration). Catch any coolant spillage
in a suitable container. 

Warning: DO NOT attempt to
remove the expansion tank filler
cap, or to disturb any part of the
cooling system, while it or the

engine is hot, as there is a very great risk
of scalding. If the expansion tank filler cap
must be removed before the engine and
radiator have fully cooled down (even
though this is not recommended) the

pressure in the cooling system must first
be released. Cover the cap with a thick
layer of cloth, to avoid scalding, and slowly
unscrew the filler cap until a hissing sound
can be heard. When the hissing has
stopped, showing that pressure is
released, slowly unscrew the filler cap
further until it can be removed; if more
hissing sounds are heard, wait until they
have stopped before unscrewing the cap
completely. At all times, keep well away
from the filler opening.
3 On completion, reconnect the hoses to the
automatic choke unit, and remove the clamps
from the hoses. Check and top-up the coolant
level on completion (see Chapter 1).

21 Automatic choke (Weber

TLD carburettor) - 
adjustment

3

1 Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2 Remove the air cleaner as described in
Section 2.
3 Disconnect the coolant hoses to the choke
unit as described in paragraph 2 of the
previous Section.
4 Note the position of the choke coil housing
alignment marks, then undo the three
retaining screws and withdraw the automatic
choke bi-metal coil housing (see illustration).
5 Remove the inner heat shield (see
illustration). To check and adjust the choke
vacuum pull-down, secure the choke plate
lever in the closed position by fitting a rubber
band, open the throttle to allow the choke
plate to fully close, then release the throttle.
6 Using a screwdriver, push the operating
arm to the right against its spring, and
measure the clearance between the lower
edge of the choke plate and the venturi using
a twist drill or other suitable gauge rod (see
illustration). Where the clearance is outside
that specified, remove the plug from the
diaphragm housing, and turn the adjuster
screw (now exposed) in the required direction.
7 Fit a new diaphragm housing plug and
remove the rubber band.
8 Refit the heat shield so that its slotted hole
engages over the choke housing peg.

4A•12 Fuel and exhaust systems – carburettor engines

21.5  Removing the inner heat shield from

the automatic choke housing

21.4  Automatic choke unit on the Weber

TLD carburettor, showing the pull-down

diaphragm housing (A) and the choke bi-

metal spring housing (B)

20.2  Coolant hose connections to the

automatic choke unit

19.3  Fast idle adjustment on the TLD

carburettor showing the adjuster screw (B)

on 4th step of the fast idle cam (A). Note

that the housing is removed for clarity

9 Refit the bi-metal coil housing by first
connecting the bi-metal spring to the choke
lever (ensuring correct engagement), locate
the housing and hand-tighten the three
retaining screws. Rotate the housing to align
the index line on the housing with the dot
mark on the choke main body, then retighten
the retaining screws (see illustration).
10 Reconnect the coolant hoses with
reference to paragraph 3 in the previous
Section.
11 Refit the air cleaner as described in
Section 2.

22 Automatic choke (Weber

TLD carburettor) - removal,
inspection and refitting

4

Warning: Petrol 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, in or near the work area. Don’t work
in a garage where a natural-gas appliance
(such as a water heater or clothes dryer)
with a pilot light is present. If you spill any
fuel on your skin, rinse it off immediately
with soap and water. When you perform
any kind of work on the fuel system, wear
safety glasses, and have a Class B type
fire extinguisher on hand.

Note: A new carburettor upper body gasket
will be required when reassembling. On
completion, a tachometer will be required to
check the fast idle speed adjustment.

Removal

1 Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2 Remove the air cleaner as described in
Section 2.
3 To prevent excess coolant loss, clamp the
coolant supply and return hoses to the
automatic choke unit, and ensure that the
cooling system is not pressurised (see
Chapter 3). Identify then detach both of the

coolant hoses at the automatic choke
housing. Catch any coolant spillage in a
suitable container. 

Warning: DO NOT attempt to
remove the expansion tank filler
cap, or to disturb any part of the
cooling system, while it or the

engine is hot, as there is a very great risk
of scalding. If the expansion tank filler cap
must be removed before the engine and
radiator have fully cooled down (even
though this is not recommended) the
pressure in the cooling system must first
be released. Cover the cap with a thick
layer of cloth, to avoid scalding, and slowly
unscrew the filler cap until a hissing sound
can be heard. When the hissing has
stopped, showing that pressure is
released, slowly unscrew the filler cap
further until it can be removed; if more
hissing sounds are heard, wait until they
have stopped before unscrewing the cap
completely. At all times, keep well away
from the filler opening.
4 Detach the fuel pipe and the anti-dieselling
solenoid wiring connector. Any crimped type
hose clips must be replaced with a screw
clamp type clips during reassembly.
5 Unscrew and remove the retaining screws
(two conventional, and four Torx type), then

lift the carburettor upper body clear and
remove it.
6 Note the position of the choke housing
alignment marks, then undo the three
retaining screws and remove the choke bi-
metal coil unit. Remove the internal heat
shield.
7 To remove the automatic choke unit, undo
the three retaining screws and detach the
choke link from the operating lever.
8 Undo the three retaining screws to remove
the vacuum diaphragm unit.
9 If dismantling the choke mechanism any
further, note the component fitment as an aid
to reassembly, but do not detach the choke
spindle (see illustration).

Inspection

10 Clean and inspect all components for
wear, damage and/or distortion. Pay
particular attention to the condition of the
vacuum (pull-down) diaphragm and the choke
housing O-ring. Renew any items that are
defective (or suspect).

Refitting

11 Reassemble the automatic choke
mechanism, making references to the notes
taken during dismantling (see illustration
22.9). Note that no lubricants must be used.
12 Refit the vacuum unit, making reference to
the notes taken during dismantling. Ensure
that the diaphragm is lying flat before
tightening the housing retaining screws.
13 Locate the O-ring (ensuring that it is
correctly seated), then reconnect the choke
link. Refit the automatic choke unit, and
secure with the retaining screws. Check and
adjust the choke vacuum pull-down as
described in the previous Section (para-
graphs 5 and 6).
14 Refit the inner heat shield, ensuring that
the location peg is securely engaged in its
notch.
15 Refit the automatic choke housing and the
bi-metal spring unit as described in the
previous Section (paragraph 9).

Fuel and exhaust systems – carburettor engines  4A•13

21.9  Index marks on the automatic choke

housing (B) and body (A) should be in

alignment

21.6  Choke plate pull-down adjustment on

the Weber TLD carburettor

A  Twist drill
B  Screwdriver in contact with operating arm
C  Adjuster screw

4A

22.9  Automatic choke unit and associated components on the Weber TLD carburettor

A   Operating link/fast idle cam
B   Fast idle cam return spring
C   Spindle
D   Connecting rod and lever assembly

E   Pull-down link
F   Actuating lever
G   Automatic choke housing

16 Refit the carburettor upper body, ensuring
that a new gasket is used and that the mating
surfaces are clean. Fit the retaining screws to
secure.
17 Reconnect the fuel hose to the
carburettor, using new screw type hose clips
to secure it.
18 Reconnect the anti-dieselling solenoid
wiring connector.
19 Reconnect the coolant hoses to the
automatic choke unit, then check and if
necessary top-up the cooling system as
described in Chapter 1.
20 Reconnect the battery earth lead, then
check and adjust the fast idle speed as
described in Section 19.
21 Refit the air cleaner (Section 2).

23 Carburettor (Weber TLD) -

removal and refitting

4

Warning: Petrol 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, in or near the work area. Don’t work
in a garage where a natural-gas appliance
(such as a water heater or clothes dryer)
with a pilot light is present. If you spill any
fuel on your skin, rinse it off immediately

with soap and water. When you perform
any kind of work on the fuel system, wear
safety glasses, and have a Class B type
fire extinguisher on hand.
Note: New gaskets will be required on refitting
and a tachometer and an exhaust gas analyser
will be required on completion.

Removal

1 Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2 Remove the air cleaner as described in
Section 2.
3 Release any pressure remaining in the
cooling system (see Chapter 3), and then
detach the two coolant hoses from the
automatic choke unit. Catch any coolant
spillage in a suitable container. Identify each
hose for subsequent refitting, then plug their
ends or position them as high as possible to
prevent coolant leakage. 

Warning: DO NOT attempt to
remove the expansion tank filler
cap, or to disturb any part of the
cooling system, while it or the

engine is hot, as there is a very great risk of
scalding. If the expansion tank filler cap
must be removed before the engine and
radiator have fully cooled down (even
though this is not recommended) the
pressure in the cooling system must first be
released. Cover the cap with a thick layer of
cloth, to avoid scalding, and slowly unscrew

the filler cap until a hissing sound can be
heard. When the hissing has stopped,
showing that pressure is released, slowly
unscrew the filler cap further until it can be
removed; if more hissing sounds are heard,
wait until they have stopped before
unscrewing the cap completely. At all times,
keep well away from the filler opening.
4 Disconnect the accelerator cable from the
linkage at the carburettor, as described in
Section 3.
5 Detach the anti-dieselling solenoid wiring
connector 

(see illustration). Where

applicable, also detach the idle speed control
motor multi-plug and the throttle position
sensor wiring multi-plug (see illustration).
6 Detach the fuel feed hose at the carburettor
(see illustration). As it is detached, plug the
end of the hose to prevent excessive fuel
spillage and the ingress of dirt. Where a
crimped type hose clip is fitted, cut it free,
taking care not to damage the hose; a new
screw clamp type clip will need to be obtained
to replace the crimped clip during reassembly.
7 Disconnect the relevant vacuum pipes from
the carburettor (see illustration). As they are
detached, label them to ensure correct
reassembly.
8 Unscrew and remove the four Torx-type
retaining screws, and carefully lift clear the
carburettor from the inlet manifold (see
illustrations). Remove the gasket.

4A•14 Fuel and exhaust systems – carburettor engines

23.8B  Undo the retaining screws  . . .

23.8A  Weber TLD carburettor showing the

four Torx-type retaining screws (A). The two

conventional screws (B) secure the upper

and lower carburettor body sections together

23.7  Disconnecting the vacuum hose from

the secondary venturi diaphragm unit

23.6  Disconnecting the fuel line at the

carburettor

23.5B  Disconnect the idle speed control

motor multi-plug (A) and the throttle position

sensor wiring multi-plug (B) where fitted

23.5A  Disconnecting the lead from the

anti-dieselling (fuel-cut off) solenoid