Chapter 1 Routine maintenance and servicing

Fuel system – carburettor engines 4A•72 Remove the filler cap surround (seeillustration).3 Disconnect the ventilation tube from thecombined roll-over/anti-trickle-fill valve,release the ventilation tube from its retainingclips and detach the valve from the vehicle.4 Remove the filler pipe securing bolt, thentwist and withdraw the filler pipe unit.5 Prior to refitting, check the condition of thefiller pipe seal in the fuel tank and renew ifnecessary.Refitting6 Refitting is a reversal of the removalprocedure, but apply a light smear of greaseto the filler pipe seal to aid filler pipe entry.12 Carburettor (Weber TLM) -descriptionThe carburettor is of the single (fixed)venturi downdraught type, featuring a fixedsize main jet system with a mechanicallyoperatedaccelerator pump and vacuumoperatedpower valve to provide optimumfuelling.A manually-operated choke system isfitted, featuring a vacuum-operated pull-downmechanism which brings the choke partiallyoff during conditions of high manifoldvacuum.An anti-dieseling (fuel cut-off) solenoid(where fitted) prevents the possibility ofengine run-on when the ignition is switchedoff.Idle speed and mixture adjustmentprocedures are described in Chapter 1, but itis important to note that accurate adjustmentscan only be made using the necessaryequipment.13 Carburettor (Weber TLM) -fast-idle speed adjustment4Note: Before carrying out any carburettoradjustments, ensure that the spark plug gapsare set as specified, and that all electrical andvacuum connections are secure. To carry outchecks and adjustments, an accuratetachometer and an exhaust gas analyser (COmeter) will be required.1 Check the idle speed and mixture settingsare as specified (as described in Chapter 1).These must be correct beforechecking/adjusting the fast-idle speed.2 With the engine at its normal operatingtemperature, and a tachometer connected inaccordance with the manufacturer’sinstructions, remove the air cleaner (if notalready done) as described in Section 2.3 Actuate the choke by pulling its controlknob fully out, then start the engine.4 Hold the choke plate open using a 5.0 mmtwist drill held between the plate and the11.2 Removing the filler cap surroundventuri, and record the fast-idle speedachieved. If adjustment is necessary, turn thefast-idle adjusting screw until the specifiedspeed is obtained (see illustration).5 Re-check the fast-idle and basic idlespeeds.6 On satisfactory completion of theadjustment, stop the engine, disconnect thetachometer and CO meter then refit the aircleaner.7 Remove the bridging wire from the radiatorcooling fan thermal switch multi-plug, andreconnect the multi-plug to the thermalswitch.14 Needle valve and float (WeberTLM carburettor) - removal, 4refitting and adjustmentNote: Refer to the warning note in Section 1before proceeding. New gaskets and a washer(seal) will be required when reassembling. Atachometer and an exhaust gas analyser (COmeter) will also be required to check the idlespeed and mixture settings on completion.Removal and refitting1 Disconnect the battery negative (earth) lead(refer to Chapter 5A, Section 1).2 Remove the air cleaner as described inSection 2.3 Clean the exterior of the carburettor, thendisconnect the fuel feed hose.4 Disconnect the choke cable and the chokevacuum hose.13.4 Fast-idle speed adjusting screw(arrowed) (Weber TLM carburettor)5 Remove the four screws securing thecarburettor upper body (two of these screwsare Torx head type), and detach it. Note thatthe carburettor lower body is now looseon the inlet manifold.6 Tap out the float retaining pin, remove thefloat and withdraw the needle valve. Unscrewthe needle valve housing, as required, notingwasher fitment.7 Inspect the components for damage andrenew as necessary. Check the needle valvefor wear, and check the float assembly forleaks by shaking it to see if it contains petrol.Whilst accessible, clean the float chamberand jets (refer to Section 17).8 Using a new washer, refit the needle valvehousing.9 Refit the needle valve, float and retainingpin, ensuring that the tag on the float engagesbetween the ball and clip on the needle valve.10 Before refitting the carburettor upperbody, check and if necessary adjust the floatlevel as described in paragraph 15 to 18. Alsocheck the float and needle valve for full andfree movement.11 Clean the gasket contact faces (includingthe inlet manifold) then, using new gaskets forthe carburettor upper body and the inletmanifold faces, refit the carburettor upperbody and secure the carburettor assembly tothe inlet manifold.12 Reconnect the choke vacuum hose. If thefuel feed hose was originally secured with acrimped type clip, discard this and secure thefuel feed hose with a nut and screw type clip.13 Reconnect and adjust the choke cable,then refit the air cleaner.14 Reconnect the battery negative lead, startand warm up the engine then check the idlespeed and mixture settings as described inChapter 1.Float level adjustment15 With the carburettor upper body removedas described in paragraphs 1 to 5 inclusive,proceed as follows.16 Hold the carburettor upper body in theposition shown (see illustration), ensuringthat the needle valve is shut off. Fit the newupper body gasket to the carburettor upper14.16 Float level adjustment (Weber TLMcarburettor)A Adjusting tagB Float level setting dimension4A1595Ford Fiesta Remake