The following adjustments may be performed with the carburetor in service. Additional adjustments are part of the overhaul procedure.
Before performing any adjustments, the following steps must be followed:
- Set the parking brake, then block both the front and rear wheels.
- Place the transaxle in Neutral (manual vehicles) or in P (automatic vehicles).
- Switch ALL accessories OFF.
- If equipped with power steering, make sure the front wheels are pointing forward. This must be done to make sure the power steering pump is not placing an additional load on the engine.
- Check and, if necessary, adjust the ignition timing.
Idle Speed and Mixture Adjustment
Refer to Engine Performance and Tune-up of this repair guide for idle speed and mixture adjustments. For additional carburetor adjustments, refer to carburetor assembly in the overhaul procedures, later in this section.
REMOVAL & INSTALLATION
See Figure 1
- Disconnect the negative battery cable.
- Properly drain the engine cooling system.
- Remove the air cleaner assembly.
- Disconnect the hoses and unplug the harness connector.
- Remove the accelerator control cable.
- Remove the carburetor mounting bolts located on the bottom side of the intake manifold.
- Remove the carburetor from the engine.
- Be sure to cover the intake manifold to prevent debris from entering and damaging the engine.
- Replace the insulator holding the Early Fuel Evaporation (EFE) heater with new packings.
- Install the carburetor and tighten the retaining bolts to 7.2 ft. lbs. (9.8 Nm).
- Connect the accelerator, then check and adjust as necessary.
- Connect the removed hoses and connectors.
- Install the air cleaner assembly.
- Connect the negative battery cable and fill the engine cooling system, then start the engine and check for leaks.
See Figures 2 and 3
Once the carburetor has been removed from the engine, and before disassembly, check for traces of abrasion, fuel leakage or other damage on each component. This may help lead to the identification of components which must be replaced.
Be sure to remove the wire pins, necessary for disassembly of each component, from the connectors. Refer to the appropriate illustration for pin locations and wire colors for each connector.
See Figures 4 through 11
- Remove the pump lever spring, then remove the pump arm assembly.
- Remove the E-clip and the connecting link from the cam lever of the automatic choke.
- Remove the 7 air horn attaching screws, then lift the air horn straight up and off the body.
- Pull out the pin and remove the float assembly.
- Remove and discard the old gasket.
- Remove the needle valve assembly, seat and packing.
- Remove the pump and piston assembly.
- Remove the 2 screws. then remove the mixture control duty solenoid valve from the air horn. Take care not to tilt of bind the valve during removal.
- Remove the choke break diaphragm unit by first removing the E-clip, then removing the coupling from the connecting link. Loosen the 2 screws, then remove the choke break diaphragm as a unit.
See Figures 12 through 22
- Remove the throttle return and 2nd lock spring.
- Remove the E-clip and remove the diaphragm chamber rod from the secondary valve shaft.
- Remove the accelerator control cable bracket bolt and the 2 screws on the bottom side of the body.
- Remove the diaphragm chamber and gasket.
- Remove the slow cut solenoid valve.
- Remove the snapring in the pump well, then take out the filter and the inlet check valve. Be VERY careful not to score the pump bore when removing the snapring.
- Remove the main jet plug retainer and remove the plug.
- Remove the primary and secondary main jets with packings.
- Remove the primary small venturi and secondary small venturi assembly.
- Remove the main air bleed jets.
- Remove the plug and take out the P-slow jet.
- Remove the plug and take out the pump injector.
- Remove the plug and take out the S-slow jet and S-slow air bleed (2nd).
- Remove the idle-up (mixture by-pass) jet.
See Figure 23
- Remove the idle-up (mixture by-pass) solenoid valve(s)
- Loosen the 2 retaining screws, then remove the Throttle Position Sensor (TPS).
- Clean all removed parts, except O-rings, packing, gaskets and electric parts, using a carburetor cleaner. Take care not to score or damage parts.
- After cleaning, remove any dirt or foreign material by blowing out each passage of the carburetor using dry compressed air.
- Check for cracks or damage to the float and for abrasion of the float pin hole.
- Check for abrasion and flaws on the float pin.
- Check for damage or abrasion on the needle valve, body and spring.
- Check for damage and abrasion on the needle valve seat and strainer.
- Inspect the pump piston for wear or damage.
- Inspect the springs and strainer for damage.
- Inspect the pump injector for damage.
- Inspect the acceleration pump piston bore for wear or scratches.
See Figure 24
- Check the valve body and spring for damage.
- Install the spring to the valve body.
- Apply 12 volts to the valve, as shown in the illustration.
- The valve should operate smoothly with power applied. If not, valve and/or air horn assembly must be replaced.
- Inspect the air horn surface for distortion, scratching or other damage and replace, if damage is found.
- Using a hand-held pump, apply vacuum to the choke break unit.
- The diaphragm should hold the vacuum for a reasonable amount of time.
- If the unit diaphragm does not hold vacuum, it must be replaced.
- Measure the resistance between the thermostatic spring lead wire and the housing using an ohmmeter.
- With an ambient temperature of 78°F (25°C), resistance should be 1-11 ohms.
See Figure 25
- Check for damage to the slow cut solenoid valve body and spring spool.
- Install the valve assembly to the body.
- Apply 12 volts to the valve terminals; refer to the illustration.
- With power applied, make sure the valve operates smoothly. If not, the valve must be replaced.DIAPHRAGM CHAMBER
- Push in diaphragm chamber rod using your fingers.
- Block the chamber hole and make sure the rod does not move.
- Check for damage to the valve body, spring and spool.
- Install the valve assembly to the flange.
- Apply 12 volts to the solenoid terminals and check that the solenoid operates smoothly.
- Replace the solenoid if it does not operate smoothly.
- Inspect the air horn, body and flange for damage, cracks or flaws on the fitting surfaces. Replace the component(s), if problems are found.
- Inspect for deformation and abrasion of the shaft, link, bushing and related components. Replace, if damage is found.
Always use new O-rings, gaskets and packings when assembling the various carburetor components.FLANGE
- If the idle mixture adjusting screw was removed, temporarily install it.
- Install the TPS to the bracket.
- Install the idle-up (mixture by-pass) solenoid valve using a new gasket.
- Check that each part moves smoothly.
- Assemble each jet in the proper position.
- Install the accelerating pump filter by first inserting the check ball, then insert the filter followed by the snapring. Be VERY CAREFUL that no damage is done to the bore while inserting the snapring.
- Install the slow cut solenoid valve using a new gasket.
- Install the diaphragm chamber using a new gasket.
- Position a new gasket on top of the flange, then position the body on top of the assembly. Install the flange screws and wire bracket, then tighten the bolt.
- Connect the diaphragm chamber rod and the secondary shift valve shaft with the E-clip.
- Install the throttle return and 2nd lock springs.
- Insert the accelerating pump return springs into the pump bore and install the piston from the top.
- Make sure each part of the assembly moves smoothly.
See Figure 26
- Install the air vent solenoid valve using a new gasket.
- Install the choke break diaphragm unit and hose. Connect the rod to the diaphragm then secure using the E-clip.
- Install the mixture control duty solenoid by passing the wires through the air horn and inserting the valve vertically, holding the valve body. DO not attempt to insert the valve while bending or holding at an angle. Tighten the retainer screw.
- Install and tighten the needle valve seat with the packing, then install the needle valve onto the valve seat.
- Install the new gasket on the air horn.
- Install the float and secure it using the float pin.
- Adjust the upper float level by checking the clearance between the float top and gasket when the float is in the raised position. Clearance should be 0.59 in. (15mm), if necessary bend tab A to adjust. Refer to the figure.
- Adjust the lower float level by checking the clearance between the float bottom and gasket when the float is in the lowered position. Clearance should be 1.7 in. (44.3mm), if necessary bend tab B to adjust. Refer to the figure.
See Figure 27
- Being careful not to bump the float against the body, assembly the air horn to the body. Check to make sure no wires are pinched between the components.
- Carefully insert the grooves of the accelerating pump piston rod and boot.
- Install the screws retaining the air horn to the body. Note that the screws are of varying lengths. Refer to the illustration for proper positioning.
- Connect the link to the choke cam lever, then install the E-clip.
- Install the pump arm assembly.
Arrange each wire properly:
- Position the slow cut solenoid valve wire on the inner side.
- Position the automatic choke heater wires on the outer side.
- Make sure the wires DO NOT interfere with the throttle valve return spring.
- Install the wires to their positions in the wiring harness connectors.
- Make sure that each carburetor part moves smoothly.
See Figures 28 through 35
- If removed, install the idle mixture screw and seat it lightly in the bore, then carefully back the screw out 3 turns from fully closed for manual transaxles or 2 turns from fully closed for automatic transaxles.
- Inspect the full open angle of the primary throttle valve. With the throttle lever fully opened, the valve angle should be 90 degrees from the horizontal plane. If necessary, adjust by carefully bending the throttle arm.
- Inspect the full open angle of the secondary throttle valve. With the throttle lever fully opened, open the secondary throttle valve completely; the valve angle should be 87 degrees from the horizontal plane. If necessary, adjust by carefully bending the secondary shaft lever.
- Inspect the opening of the secondary valve when just the primary throttle valve is fully opened. The secondary valve angle should be 23 degrees from the horizontal plane. If necessary, adjust by carefully bending the secondary shaft lever.
- Inspect the secondary touch angle. Measure the primary throttle valve opening, at the position where the secondary valve begins to open. Clearance between the valve plate and bore should be 0.23 in. (5.87mm). If necessary, adjust by carefully bending the throttle adjusting arm.
- Inspect the choke valve in the third step of the fast idle cam. Set the choke fully open, then slowly open the throttle lever while lightly pushing (with your fingers) the choke valve in the closing direction and set the choke valve to the third stage of the fast idle cam.
- Check the choke valve clearance; it should be 0.086 in. (2.19mm). If not to specification, remove the rivet of the auto choke and adjust by bending the choke lever in the housing. After adjustment always be sure to install the choke cover by riveting.
- Inspect the primary throttle valve clearance in the second stage of the fast idle cam. Set the choke fully open, then slowly open the throttle valve while lightly pushing (with your fingers) the choke valve in the closing direction and set the choke valve to the second stage of the fast idle cam.
- Check the primary throttle clearance; it should be 0.0323 in. (0.82mm) for automatic transaxle vehicles or 0.0256 in. (0.65mm) for manual transaxle vehicles. If necessary, adjust the fast idle screw to achieve the proper clearance.
- Check the unloader by fully opening the primary throttle valve, then measuring the choke valve clearance; it should be 0.071 in. (1.8mm). If not to specification, remove the auto choke rivet and adjust by bending the choke lever in the housing. After adjustment, always be sure to install the choke cover by riveting.
- Check the choke break using a hand held vacuum pump. Apply 400mm Hg to the choke break vacuum unit and measure the valve clearance while lightly pushing the valve towards the closing side. Clearance should be 0.057 in. (1.44mm). If necessary, adjust by bending the choke lever.
Check and, if necessary, adjust the TPS. Checking and adjustment of the sensor should be completed as quickly as possible:
- Make sure the TPS bracket screws are tight.
- Make sure there is not play in the TPS arm and primary throttle arm.
- Connect an ohmmeter across the green and black leads of the TPS terminal.
- Open the primary throttle lever about 1 / 3 , the ohmmeter should indicate NO CONTINUITY. Gradually close the lever and check that there is continuity when the primary throttle valve reaches the prescribed clearance. Specified clearance is 0.015 in. (automatic transaxle vehicles) or 0.011 in. (manual transaxle vehicles).
- If not to specification, loosen the retaining screws and adjust the switch to achieve the proper angle. After tightening the screws, check clearance adjustment again using the ohmmeter.