Ford Orion. Manual - part 33

Refitting

3 Refit in the reverse order of removal.
Lubricate the filler pipe seal to ease assembly
prior to fitting.
4 When the fuel tank is refitted, refill with fuel,
and check for any signs of leaks from the filler
pipe and associated connections.

12 Carburettor (Weber TLDM) -

description

The carburettor is of twin venturi,

downdraught type, featuring a fixed size main
jet system, adjustable idle system, a
mechanically-operated accelerator pump, and
a vacuum-operated power valve. A manually-
operated cold start choke is fitted, and a
throttle kicker is utilised on some models (see
illustration).

In order to comply with emission control

regulations and maintain good fuel
consumption, the main jets are calibrated to
suit the 1/4 to 3/4 throttle range. The
power valve is therefore only used to
supply additional fuel during full-throttle
conditions.

The accelerator pump is fitted to ensure a

smooth transmission from the idle circuit to
the main jet system. As the accelerator pedal
is depressed, a linkage moves the diaphragm
within the accelerator pump, and a small
quantity of fuel is injected into the venturi, to
prevent a momentary weak mixture and
resultant engine hesitation.

The manually-operated choke features a

vacuum-operated pull-down mechanism
which controls the single choke plate under
certain vacuum conditions.

The throttle kicker (where fitted) acts as an

idle speed compensator, which operates
when required under certain operating
conditions to prevent stalling.

An anti-dieselling (fuel cut-off) solenoid is

fitted to prevent the possibility of the engine
running on after the ignition is switched off.

Adjustment procedures are described in

Chapter 1, but it is important to note that
accurate adjustments can only be made using
the necessary equipment.

13 Carburettor (Weber TLDM) -

fast idle adjustment

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 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 Actuate the choke by pulling the control
knob fully out, then start the engine and note
the engine fast idle speed. Compare it with
the specified speed.
4 If adjustment is required, turn the fast idle
adjuster screw clockwise to decrease, or anti-
clockwise to increase, the fast idle speed (see
illustration).
5 Recheck the fast idle and basic idle speeds.
6 On completion of the adjustment, stop the
engine, detach the tachometer and CO meter,
reconnect the radiator cooling fan lead, and
refit the air cleaner.

Fuel and exhaust systems – carburettor engines 4A•7

12.1 Exploded view of the Weber TLDM carburettor

13.4 Fast idle adjuster screw location (A)

in the Weber TLDM carburettor

A   Anti-dieselling (fuel cut-off) solenoid
B   Emulsion tubes
C   Air correction jets
D   Choke pull-down diaphragm unit
E   Manual choke linkage
F   Needle valve
G   Float
H   Fast idle adjustment screw

J   Idle speed adjustment screw
K   Fuel mixture adjustment screw
L   Throttle plates
M   Power valve
N   Accelerator pump
P   Throttle kicker (where fitted)
Q   Upper body gasket
R   Main jets

14 Needle valve and float (Weber

TLDM carburettor) - removal,
refitting and adjustment

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 and a washer (seal) will be
required when reassembling. A tachometer
and an exhaust gas analyser (CO meter) will
also be required to check the idle speed and
mixture settings on completion.

Removal and refitting

1 Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2 Remove the air cleaner as described in
Section 2.
3 Clean the exterior of the carburettor, then
disconnect the fuel supply hose and the anti-
dieselling solenoid wiring.
4 Disconnect the choke control cable.
5 Undo and remove the six retaining screws
(four of which are Torx type) and carefully lift
the carburettor upper body clear.
6 Invert and support the upper body of the
carburettor for access to the float and pivot.
Lightly tap out the float pivot pin, then
withdraw the float, taking care not to distort
the arms of the float (see illustrations).
7 Unscrew the needle valve housing, and
extract it from the carburettor upper body
(see illustration). Collect the washer from the
threads of the needle valve housing.
8 Clean and inspect the components for
signs of damage or wear, particularly the pivot
holes in the float arm. Check the float for signs
of leakage, by shaking it to see if it contains
fuel. Clean the float chamber and jets (refer to

Section 17 for details). Renew any
components as necessary.
9 Fit a new washer over the needle valve
housing threads, and then carefully screw the
valve unit into position in the upper body.
10 Refit the needle valve, float and retaining
pin, ensuring that the tag on the float engages
with the ball and clip of the needle valve.
11 Before refitting the upper body to the
carburettor, check and if necessary adjust the
float level as described in paragraphs 16 to
18. Also check the float and needle valve for
free movement.
12 Clean the gasket contact faces, then
locate a new gasket and refit the upper body
to the carburettor.
13 Reconnect the fuel supply hose, anti-
dieselling solenoid wiring and the choke
cable. Adjust the choke cable as described in
Section 6. If the fuel hose was originally
secured with a crimped type clip, discard it
and fit a screw clamp type.
14 Refit the air cleaner as described in
Section 2.
15 Reconnect the battery earth lead, then
restart the engine and check the idle speed
and mixture settings. Adjust if necessary as
described in Chapter 1.

Float level adjustment

16 With the carburettor upper body removed
as described in paragraphs 1 to 5 inclusive,
proceed as follows.
17 Support the carburettor upper body
vertically, ensuring that the needle valve is

shut off. Locate the new upper body gasket
onto the carburettor upper body, then
measure the distance between the gasket and
the bottom of the float (see illustration).
18 If the measurement is not as specified,
adjust the setting by carefully bending the tag
on the float as required, then recheck.
19 Refit with reference to paragraphs 12 to
15 inclusive.

15 Throttle kicker unit (Weber

TLDM carburettor) - removal,
refitting and adjustment

Note: A tachometer and exhaust gas analyser
(CO meter) will be required to check and make
any adjustment necessary.

Removal and refitting

1 Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2 Refer to Section 2 and remove the air
cleaner.
3 Detach the vacuum hose from the kicker
unit. Undo the two retaining screws, detach
the linkage and remove the kicker unit.
4 Refitting the kicker unit is a reversal of the
removal procedure. If the unit is to be
checked for adjustment, loosely locate the air
cleaner, reconnect the intake air temperature
sensor multi-plug and the battery earth lead,
then proceed as follows.

Adjustment

5 Start and run the engine up to its normal
operating temperature (at which point the
cooling fan will start to operate) then switch
the engine off.
6 Remove the air cleaner again, then detach
the wiring connector of the cooling fan
thermostatic switch. Bridge the terminals in
the connector with a suitable piece of wire to
actuate the cooling fan and keep it running.
Start the engine and run it at 3000 rpm for
30 seconds to stabilise it, then release the
throttle and check (and if necessary adjust)
the idle speed and mixture settings as
described in Chapter 1. Stop the engine.
7 Detach the vacuum hose between the
throttle kicker and the inlet manifold at source

4A•8 Fuel and exhaust systems – carburettor engines

14.17 Checking the float level adjustment

(TLD carburettor shown) - adjustment tag

arrowed

14.7 Remove the needle valve housing and

its washer

14.6B . . . then detach the float and needle

valve

14.6A Slide out the float retaining pin . . .

(but not the vacuum supply to the ignition
module). Connect a new length of vacuum
hose directly between the manifold and the
kicker unit.
8 Restart the engine and check the engine
speed. The throttle kicker should increase the
engine speed above its normal idle. Check the
speed registered against the specified throttle
kicker operating speed.
9 If required, the throttle kicker speed can be
adjusted by prising free the tamperproof plug
and the adjustment screw turned as
necessary

(see illustration).

10 When the adjustment is complete, stop
the engine, fit a new tamperproof plug,
disconnect the temporary vacuum hose
(between the manifold and the kicker unit) and
reconnect the original hose (between the
carburettor and the kicker unit).
11 Remove the bridging wire, and reconnect
the cooling fan thermostatic switch multi-
plug. Refit and secure the air cleaner, and
disconnect the tachometer and CO meter to
complete.

16 Carburettor (Weber TLDM) -

removal and refitting

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 type
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 Disconnect the accelerator cable from the
carburettor (Section 3).
4 Disconnect the choke cable from the
carburettor (Section 6).
5 Disconnect the fuel hose from the
carburettor, and plug its end to prevent fuel
spillage and the ingress of dirt. If a crimped
type hose clip is fitted, cut it free, but take
care not to damage the hose. Crimped clips
must be discarded and replaced with screw
clamp type clips during refitting.
6 Disconnect the wiring from the anti-
dieselling solenoid.
7 Unscrew and remove the four carburettor-
to-manifold retaining Torx head screws, then
carefully lift the carburettor from the manifold.

Refitting

8 Clean the carburettor and manifold gasket
mating faces.
9 Refit in the reverse order of removal. Fit a
new gasket, and tighten the retaining screws
securely. Ensure that the fuel supply hose
connection to the carburettor is securely
fitted, using a new screw clamp retaining clip.
10 Reconnect the accelerator cable, and
adjust it as described in Section 3.
11 Reconnect the choke cable, and adjust it
as described in Section 6.
12 Refer to Section 2 and refit the air cleaner.
13 When the battery is reconnected, start the
engine and check the idle speed and mixture
settings as described in Chapter 1.

17 Carburettor (Weber TLDM) -

dismantling, cleaning,
inspection and reassembly

Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t

Note: Check parts availability before
dismantling. If possible, obtain an overhaul kit
containing all the relevant gaskets, seals, etc,
required for reassembly prior to dismantling
the carburettor.

Dismantling

1 With the carburettor removed from the
vehicle, prepare a clean, flat work surface
prior to commencing dismantling. The
following procedures may be used for partial
or complete dismantling, as required.
2 Clean the exterior of the carburettor, then
undo the two retaining screws and lift the
upper carburettor body from the lower section
(see illustrations).
3 Remove the float and needle valve from the
carburettor upper body, as described in
Section 14.
4 Unscrew and remove the anti-dieselling
solenoid from the upper body, but ensure that
the seal washer is removed together with the
valve. (see illustration).
5 Undo the three screws securing the choke
mechanism, and detach it (see illustrations).
6 Unscrew and remove the two air correction
jets from the underside of the upper body.
Note the size and location of each, to ensure
correct refitting.
7 Invert the upper body so that the emulsion
tubes can fall out of their apertures (above the
air correction jets). Remove the emulsion

Fuel and exhaust systems – carburettor engines 4A•9

15.9 Throttle kicker unit showing

adjustment point (A), vacuum take-off (B)

and unit retaining screws (C)

17.4 Extracting the anti-dieselling (fuel

cut-off) solenoid

17.2B . . . and remove the carburettor

upper body

17.2A Undo the retaining screws . . .

tubes from their locations, again having noted
the size and location of each.
8 Unscrew and remove the main jets, again
having noted their fitted positions.
9 Dismantle the carburettor lower (main) body
as follows.
10 Prise free the accelerator pump discharge
tube, but take care not to damage it or the
carburettor body (see illustration).
11 Undo the four screws securing the
accelerator pump; remove the cover, followed
by the diaphragm and return spring. The valve
should come out on the end of the return
spring (see illustrations). Check that the
valve is complete and with its O-ring seal
(where applicable).
12 Undo the three retaining screws, and
remove the power valve unit. Remove the
cover and return spring, followed by the
diaphragm (see illustrations).
13 Where fitted, undo the retaining screws
and remove the throttle kicker unit from the
lower (main) body.
14 Prise free and remove the tamperproof
seal, then unscrew and remove the fuel
mixture screw (see illustration).
15 Undo the retaining screws, and remove
the throttle housing from the carburettor main
body (see illustration).

Cleaning and inspection

16 Wash the carburettor components,
drillings and passages with clean petrol, then
blow them dry using a low-pressure air line. A

4A•10 Fuel and exhaust systems – carburettor engines

17.15 Separating the throttle housing from

the carburettor main body

17.14 Unscrew and remove the fuel

mixture screw

17.12B . . . then detach the cover, return

spring and diaphragm

17.11B . . . followed by the diaphragm . . .

17.11A Remove the cover from the

accelerator pump cover . . .

17.12A Undo the power valve assembly

securing screws . . .

17.11C . . . and the return spring and valve

unit

17.10 Carefully prise out the accelerator

pump discharge tube assembly

17.5B . . . and undo the three retaining

screws (arrowed) to detach the

mechanism

17.5A Detach the choke plate operating

link . . .

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