Chapter 1 Routine maintenance and servicing

1595Ford Fiesta Remake4A•16 Fuel system – carburettor engines31.3 Fast-idle speed adjustment(Weber TLD carburettor) (Housing cutaway for illustration clarity)A Fast-idle camB Fast-idle speed adjusting screw on thirdstep of camtachometer and an exhaust gas analyser (COmeter) will be required.1 Check that the idle speed and mixturesettings are as specified (as described inChapter 1). These must be correct beforechecking/adjusting the fast-idle speed.2 Switch the engine off, then remove the aircleaner as described in Section 2.3 With the engine at its normal operatingtemperature and a tachometer connected inaccordance with its manufacturer’sinstructions, hold the throttle linkage partlyopen, then close the choke plate until the fastidleadjusting screw aligns with the third(middle) step on the fast-idle cam (seeillustration). Release the throttle linkage sothat the fast-idle speed adjusting screw restson the cam. Release the choke plate. Thelinkage will hold it in the fast-idle speedsetting position, as long as the acceleratorpedal is not depressed.4 Without touching the accelerator pedal,start the engine and record the fast-idle speedachieved. If adjustment is required, turn thefast-idle speed adjusting screw until thespecified fast-idle speed is obtained.5 When the throttle linkage is opened, thechoke plate should return to its fully-openposition. If this does not happen, either theengine is not at its normal operatingtemperature, or the automatic chokemechanism is faulty.6 Switch off the engine and disconnect thetachometer. Refit the air cleaner.32 Needle valve and float (WeberTLD carburettor) - removal, 4refitting and adjustment1 Refer to Section 20 and proceed asdescribed, noting the following difference.2 In paragraph 4, ignore the instruction todetach the choke cable (an automatic chokeis fitted to the TLD type carburettor). Instead,clamp the coolant supply and return hoseswhich lead to the automatic choke unit tominimise coolant loss, then ensure that thecooling system is not pressurised (seeChapter 1). Identify then detach both of thecoolant hoses at the automatic chokehousing. Catch any coolant spillage in asuitable container.Warning: DO NOT attempt toremove the expansion tank fillercap, or to disturb any part of thecooling system, while it or theengine is hot, as there is a very great riskof scalding. If the expansion tank filler capmust be removed before the engine andradiator have fully cooled down (eventhough this is not recommended) thepressure in the cooling system must firstbe released. Cover the cap with a thicklayer of cloth, to avoid scalding, and slowlyunscrew the filler cap until a hissing soundcan be heard. When the hissing hasstopped, showing that pressure isreleased, slowly unscrew the filler capfurther until it can be removed; if morehissing sounds are heard, wait until theyhave stopped before unscrewing the capcompletely. At all times, keep well awayfrom the filler opening.3 On completion, reconnect the hoses to theautomatic choke unit, and remove the clampsfrom the hoses. Check and top-up the coolantlevel on completion (see “Weekly Checks” andChapter 1).33 Automatic choke (WeberTLD carburettor) - adjustment31 Disconnect the battery negative (earth) lead(refer to Chapter 5A, Section 1).2 Remove the air cleaner as described inSection 2.3 Disconnect the coolant hoses to the chokeunit as described in paragraph 2 of theprevious Section.4 Note the position of the choke coil housingalignment marks, then undo the threeretaining screws and withdraw the automaticchoke bi-metal coil housing (see illustration).5 Remove the inner heat shield (seeillustration). To check and adjust the chokevacuum pull-down, secure the choke platelever in the closed position by fitting a rubberband, open the throttle to allow the chokeplate to fully close, then release the throttle.6 Using a screwdriver, push the operatingarm to the right against its spring, andmeasure the clearance between the loweredge of the choke plate and the venturi usinga twist drill or other suitable gauge rod (seeillustration). Where the clearance is outsidethat specified, remove the plug from thediaphragm housing, and turn the adjustingscrew (now exposed) in the required direction.7 Fit a new diaphragm housing plug andremove the rubber band.8 Refit the heat shield so that its slotted holeengages over the choke housing peg.9 Refit the bi-metal coil housing by firstconnecting the bi-metal spring to the chokelever (ensuring correct engagement), locatethe housing and hand-tighten the threeretaining screws. Rotate the housing to alignthe index line on the housing with the dotmark on the choke main body, then retightenthe retaining screws.10 Reconnect the coolant hoses withreference to paragraph 3 in the previousSection.11 Refit the air cleaner as described inSection 2.33.4 Automatic choke housing alignment(Weber TLD carburettor)A Dot punch markB Choke housing alignment mark33.5 Automatic choke internal heatshield(Weber TLD carburettor)33.6 Choke plate pull-down adjustment(Weber TLD carburettor)A Twist drill C Adjusting screwB Diaphragm held fully open