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    1989 Chevrolet Truck S10 P/U 2WD 2.5L TBI 4cyl

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    1720 S RIDGEWOOD A
    (386) 427-1210

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    Ford Ranger/Bronco II 1983-1990 Repair Guide

    Carburetor

    Print

    The carburetor identification tag is attached to the carburetor. To obtain replacement parts, it is necessary to know the part number prefix, suffix and, in some cases, the design change code. If the carburetor is ever replaced by a new unit, make sure that the identification tag stays with the new carburetor and the vehicle.

    REMOVAL & INSTALLATION



    1. Remove the air cleaner.
    2.  
    3. Remove the throttle cable and transmission linkage from the throttle lever. Disconnect all vacuum lines, emission hoses, the fuel line and electrical connections.
    4.  
    5. Remove the carburetor retaining nuts then remove the carburetor. Remove the carburetor mounting gasket, spacer (if so equipped), and the lower gasket from the intake manifold.
    6.  
    7. Before installing the carburetor, clean the gasket mounting surfaces of the spacer and carburetor. Place the spacer between two new gaskets and position the spacer and the gaskets on the intake manifold. Position the carburetor on the spacer and gasket and secure it with the retaining nuts. To prevent leakage, distortion or damage to the carburetor body flange, snug the nuts, then alternately tighten each nut in a criss-cross pattern.
    8.  
    9. Connect the inline fuel line, throttle cable, transmission linkage and all electrical connections and vacuum lines on the carburetor.
    10.  
    11. Adjust the engine idle speed, the idle fuel mixture and install the air cleaner.
    12.  

    FLOAT AND FUEL LEVEL ADJUSTMENTS



    Aisan Model Y Feedback 1-bbl (Dry Adjustment)

    See Figures 1, 2 and 3



    Click image to see an enlarged view

    Fig. Fig. 1: Float sight glass check



    Click image to see an enlarged view

    Fig. Fig. 2: Float level adjustment



    Click image to see an enlarged view

    Fig. Fig. 3: Float arm adjustment

    Stabilize engine temperature. With vehicle parked on a level surface and running at curb idle, check that fuel level is within the limits on sight glass as shown, If not, proceed as follows.

    1. Remove carburetor air horn from carburetor. Remove and discard air horn gasket.
    2.  
    3. Remove power valve piston and spring.
    4.  
    5. Invert air horn assembly. Using a drill of the specified diameter (0.232 in. or 4.2mm), check the clearance between the top of the float and bottom surface of air horn.
    6.  

    The float lever should be resting on needle pin when checking clearance.

    1. If required, bend float air as shown to adjust float level.
    2.  


    CAUTION
    Do not load the needle when adjusting the float. Also, do not bend the tab at the end of the float arm. This tab prevents the float from striking the bottom of the fuel bowl when empty. Refer to float drop adjustments.

    1. Install power valve piston and spring.
    2.  
    3. install air horn on carburetor, using a new air horn gasket.
    4.  
    5. Install carburetor on engine.
    6.  
    7. check ISC motor maximum extension rpm, adjust as necessary.
    8.  

    Carter Model YFA & YFA Feedback 1-bbl (Dry Adjustment)

    See Figure 4



    Click image to see an enlarged view

    Fig. Fig. 4: Measure the float drop using a homemade gauge

    1. Remove the air cleaner.
    2.  
    3. Disconnect the choke heat tube at the carburetor air horn. Disconnect the fuel inlet line at the filter.
    4.  
    5. Disconnect the electric choke wire at the connector.
    6.  
    7. Remove the wire clip retaining the link joining the fast idle choke lever to the fast idle cam and remove the link. Remove the air horn assembly attaching screws, dashpot and bracket assembly and air horn gasket. Discard the gasket.
    8.  
    9. Fabricate a float level gauge to the specified float level dimension. Refer to the Carburetor Specification chart for dimensions.
    10.  
    11. Invert the air horn assembly, and check the clearance from the float indentation on the top of the float to the bottom of the air horn with the float level gauge. Hold the air horn at eye level when gauging the float level. The float arm (lever) should be resting on the needle pin. Do not load the needle when adjusting the float. Bend the float arm as necessary to adjust the float level (clearance). Do not bend the tab at the end of the float arm. It prevents the float from striking the bottom of the fuel bowl when empty.
    12.  
    13. Install a new air horn to main body gasket. Make sure all holes in the new gasket have been properly punched and that no foreign material has adhered to the gasket. Install the air horn assembly, connect vent line to canister (if so equipped), and bracket assembly and air horn attaching screws and tighten to 25-13 in. lbs. Position the link and plastic bushing joining the fast idle cam to the fast idle choke lever and retain in place on the fast idle cam with the plastic bushing and wire clip. Make sure the mechanical fuel bowl vent rod is engaged with the forked actuating lever (if so equipped).
    14.  
    15. Connect the fuel inlet line to the fuel filter.
    16.  
    17. Connect the electric choke wire.
    18.  
    19. Install the air cleaner. Starter the engine and run it until normal operating temperature is reached. Adjust the idle fuel mixture and idle speed.
    20.  

    Motorcraft Model 1910 2-bbl (Wet Adjustment)

    See Figure 5



    Click image to see an enlarged view

    Fig. Fig. 5: When measuring the float level with a ruler, ensure that it is within 1/2 in. from the bowl corner

    1. Operate the engine until it reaches normal operating temperature. Place the vehicle on a level surface and stop the engine.
    2.  
    3. Remove the carburetor air cleaner assembly.
    4.  
    5. Remove the air horn attaching screws and the carburetor identification tag. Temporarily, leave the air horn and gasket in position on the carburetor main body and start the engine. Let the engine idle for a few minutes, then rotate the air horn out of the way and remove the air horn gasket to provide access to the float assembly.
    6.  
    7. While the engine is idling, use a scale to measure the vertical distance from the top machined surface of the carburetor main body to the level of the fuel in the fuel bowl. The measurement must be made at least 1 / 2 in. away from any vertical surface to assure an accurate reading, because the surface of the fuel is concave, being higher at the edges than the center. Care must be exercised to measure the fuel level at the point of contact with the float.
    8.  
    9. If any adjustment is required, stop the engine to minimize the hazard of fire due to spilled gasoline. To adjust the fuel level, bend the float tab contacting the fuel inlet valve upward in relation to the original position to raise the fuel level, and downward to lower it. Each time the float is adjusted, the engine must be started and permitted to idle for a few minutes to stabilize the fuel level. Check the fuel level after each adjustment, until the specified level is obtained.
    10.  
    11. Assemble the carburetor in the reverse order of disassembly, using a new gasket between the air horn and the main carburetor body.
    12.  

    FLOAT DROP ADJUSTMENT



    Aisan Model Y Feedback 1-bbl Carburetor

    See Figure 6



    Click image to see an enlarged view

    Fig. Fig. 6: Exploded view of the float assembly and related components

    1. Remove carburetor air horn from carburetor. Remove and discard air horn gasket.
    2.  
    3. Hold air horn upright and let float hang free. Using Vernier calipers, measure the maximum dimension from toe end of float to casting surface. Hold air horn at eye level when gauging the dimension.
    4.  
    5. The float drop dimension should be as shown in the Carburetor Chart. Adjust to specification by bending tab as shown.
    6.  
    7. Install air horn on carburetor, using a new air horn gasket.
    8.  
    9. Check ISC motor maximum extension rpm and adjust as necessary.
    10.  

    Carter Model YFA & YFA Feedback 1-bbl

    See Figure 7



    Click image to see an enlarged view

    Fig. Fig. 7: Measure the float drop dimension as shown

    1. Remove the air cleaner.
    2.  
    3. Disconnect the choke heat tube at the carburetor air horn. Disconnect the fuel inlet line at the filter.
    4.  
    5. Disconnect the electric choke wire at the connector.
    6.  
    7. Remove the wire clip retaining the link joining the fast idle choke lever to the fast idle cam and remove the link. Remove the air horn assembly attaching screws, dashpot and bracket assembly and air horn gasket. Discard the gasket.
    8.  
    9. Fabricate a float drop gauge to the specified dimension 14mm minimum.
    10.  
    11. Hold the air horn upright and let the float hang free. Measure the maximum clearance from the foe end of the float to the casting surface. Hold the air horn at eye level when gauging the dimension.
    12.  
    13. To adjust, bend the tab at the end of the float arm to obtain the specified setting.
    14.  
    15. Install a new air horn to main body gasket. Make sure all holes in the new gasket have been properly punched and that no foreign material has adhered to the gasket. Install the air horn assembly, connect vent line to canister (if so equipped, and bracket assembly and air horn attaching screws and tighten to 25-13 in. lbs. Position the link and plastic bushing joining the fast idle cam to the fast idle choke lever and retain in place on the fast idle cam with the plastic bushing and wire clip. Make sure the mechanical fuel bowl vent rod is engaged with the forked actuating lever (if so equipped).
    16.  
    17. Connect the fuel inlet line to the fuel filter.
    18.  
    19. Connect the electric choke wire.
    20.  
    21. Install the air cleaner. Start the engine and run it until normal operating temperature is reached. Adjust the idle fuel mixture and idle speed.
    22.  

    FAST IDLE SPEED ADJUSTMENT



    Carter YFA & YFA Feedback 1-bbl

    See Figure 8



    Click image to see an enlarged view

    Fig. Fig. 8: YFA fast idle speed control and adjustment points

    1. Place the transmission in Neutral or Park.
    2.  
    3. Bring the engine to normal operating temperature.
    4.  
    5. Turn the ignition key to the Off position.
    6.  
    7. Put the air conditioner selector in the Off position.
    8.  
    9. Disconnect the vacuum hose at the EGR valve and plug.
    10.  
    11. Place the fast idle RPM adjusting screw on the specified step of the fast idle cam.
    12.  
    13. Start the engine without touching the accelerator pedal: Check/adjust fast idle RPM to specification. Refer to the under hood sticker for specifications.
    14.  
    15. Rev the engine momentarily, allowing the engine to return to idle and turn the ignition key to the Off position.
    16.  
    17. Remove the plug from the EGR vacuum hose and reconnect it.
    18.  

    Motorcraft Model 1910A 2-bbl

    See Figure 9



    Click image to see an enlarged view

    Fig. Fig. 9: 1910 fast idle speed adjustment points

    1. Place the transmission in park or neutral.
    2.  
    3. Bring the engine to normal operating temperature.
    4.  
    5. Disconnect the plug the vacuum hose at the EGR and purge valves.
    6.  
    7. Place the fast idle lever on the V step of the fast idle cam.
    8.  
    9. Adjust the fast idle rpm to specifications.
    10.  
    11. Reconnect the EGR and purge vacuum hoses.
    12.  

    ACCELERATING PUMP STROKE ADJUSTMENT



    Motorcraft Model 1910A 2-bbl

    See Figure 10



    Click image to see an enlarged view

    Fig. Fig. 10: Accelerator pump stroke adjustment points (circled numbers)

    The accelerating pump stroke has been factory set for a particular engine application and should not be readjusted. If the stroke has been changed from the specified hole reset to specifications by following these procedures

    1. Using a blunt-tipped punch, remove and retain the roll pin from the accelerator pump cover.
    2.  

    Support the area under the roll pin when removing the pin.

    1. Rotate the pump link and rod assembly until the keyed end of the assembly is aligned with the keyed hole in the pump over-travel lever.
    2.  
    3. Reposition the rod and swivel assembly in the specified hole and reinstall the pump link in the accelerator pump cover.
    4.  

    A service accelerator rod and swivel assembly is available and must be used if replacement is necessary.

    Adjustment holes are not provided on the temperature compensated accelerator pump carburetors.

    1. Reinstall the rod pin.
    2.  

    CHOKE PULLDOWN ADJUSTMENT



    Carter YFA & YFA Feedback

    See Figure 11



    Click image to see an enlarged view

    Fig. Fig. 11 Adjust the YFA choke plate pulldown using the proper sized gauge (or drill)

    1. Remove the air cleaner assembly.
    2.  
    3. Hold the throttle plate fully open and close the choke plate as far as possible without forcing it. Use a drill of the proper diameter to check the clearance between the choke plate and air horn. Refer to the Carburetor Specification chart for specifications.
    4.  
    5. If the clearance is not within specification, adjust by bending the arm on the choke trip lever of the throttle lever. Bending the arm downward will decrease the clearance, and bending it upward will increase the clearance. Always recheck the clearance after making any adjustment.
    6.  

    Motorcraft 1910A

    See Figure 12



    Click image to see an enlarged view

    Fig. Fig. 12: Apply vacuum to the choke pull down diaphragm to check the 1910 choke plate pulldown adjustment

    1. Set throttle on fast idle cam top step.
    2.  
    3. Note index position of choke bi-metallic cap. Loosen retaining screws and rotate cap 70° in the rich (closing) direction.
    4.  
    5. Activate pulldown motor by manually forcing pulldown control diaphragm link in the direction of applied vacuum or by applying vacuum to external vacuum tube.
    6.  
    7. Measure vertical hard gauge clearance between choke plate and center of carburetor air horn wall nearest fuel bowl.
    8.  

    Pulldown setting should be within specifications for minimum choke plate opening.

    If choke plate pulldown is found to be out of specification, reset by adjusting diaphragm stop on end of choke pulldown diaphragm.

    If pulldown is reset, cam clearance should be checked and reset if required.

    After pulldown check is completed, reset choke bi-metallic cap to recommended index position as specified in the Carburetor Specifications Chart. Check and reset fast idle speed to specifications if necessary.

    SECONDARY TOUCH CLEARANCE



    Aisan Model Y Carburetor

    See Figures 13, 14 and 15



    Click image to see an enlarged view

    Fig. Fig. 13: Open the throttle until the secondary touch adjustment tang just touches the kicker lever



    Click image to see an enlarged view

    Fig. Fig. 14: Check the clearance between the primary throttle plate and the bore wall



    Click image to see an enlarged view

    Fig. Fig. 15: If adjustment is necessary, bend the secondary touch adjustment tang until the proper clearance is obtained

    1. Remove carburetor from vehicle, as described.
    2.  
    3. Check and adjust secondary touch clearance as follows:
      1. Open throttle until secondary touch adjustment tang just touches secondary kicker lever.
      2.  
      3. Using a drill of the specified diameter, check the clearance between the primary throttle plate and the wall of the bore.
      4.  
      5. If required, adjustment is made by bending secondary touch adjustment tang located on the primary throttle lever.
      6.  

    4.  
    5. Install carburetor onto engine.
    6.  

    SECONDARY KICK CLEARANCE



    Aisan Model Y Carburetor

    See Figure 16

    1. Remove carburetor from vehicle as described.
    2.  
    3. Check and adjust secondary kick clearance as follows:
      1. Open primary throttle to wide-open throttle.
      2.  
      3. Using a drill of the specified diameter, check the clearance between the secondary throttle plate and the wall of the bore.
      4.  
      5. If required, adjustment is made by bending the secondary kick tang on the secondary throttle lever.
      6.  

    4.  
    5. Install carburetor onto engine.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 16: Checking secondary kick clearance adjustment

    OVERHAUL



    See Figures 17, 18, 19, 20, 21 and 22

    Efficient carburetion depends greatly on careful cleaning and inspection during overhaul since dirt, gum, water or varnish in or on the carburetor parts are often responsible for poor performance.

    Overhaul the carburetor in a clean, dust free area. Carefully disassemble the carburetor, referring often to the exploded views. Keep all similar and look-alike parts segregated during disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

    When the carburetor is disassembled, wash all parts (except diaphragms, electric choke unit, pump plunger and any other plastic, leather, fiber, or rubber parts) in clean carburetor solvent. Do not leave the parts in the solvent any longer than is necessary to sufficiently loosen the dirt and deposits. Excessive cleaning may remove the special finish from the float bowl and choke valve bodies, leaving these parts unfit for service. Rinse all parts in clean solvent and blow them dry with compressed air or allow them to air dry, while resting on clean, lint less paper. Wipe clean all cork, plastic, leather and fiber parts with a clean, lint-free cloth.

    Blow out all passages and jets with compressed air and be sure that there are no restrictions or blockages. Never use wire or similar tools to clean jets, fuel passages or air bleeds. Clean all jets and valves separately to avoid accidental interchange.

    Examine all parts for wear or damage. If wear or damage is found, replace the defective parts. Especially, inspect the following:

    1. Check the float needle and seat for wear. If wear is found, replace the complete assembly.
    2.  
    3. Check the float hinge pin for wear and the float(s) for dents or distortion. Replace the float if fuel has leaked into it.
    4.  
    5. Check the throttle and choke shaft bores for wear or an out-of-round condition. Damage or wear to the throttle arm, shaft or shaft bore will often require replacement of the throttle body. These parts require a close tolerance of fit; wear may allow air leakage, which could affect starting and idling.
    6.  

    Throttle shafts and bushings are not normally included in overhaul kits. They can be purchased separately.

    1. Inspect the idle mixture adjusting needles for burrs or grooves. Any such condition requires replacement of the needle, since you will not be able to obtain a satisfactory idle.
    2.  
    3. Test the accelerator pump check valves. They should pass air one way, but not the other. Test for proper seating by blowing and sucking on the valve. Replace the valve as necessary. If the valve is satisfactory, wash the valve again to remove moisture.
    4.  
    5. Check the bowl cover for warped surfaces with a straightedge.
    6.  
    7. Closely inspect the valves and seats for wear and damage, replacing as necessary.
    8.  
    9. After the carburetor is assembled, check the choke valve for freedom of operation.
    10.  

    Carburetor overhaul kits are recommended for each overhaul. These kits contain all gaskets and new parts to replace those which deteriorate most rapidly. Failure to replace all of the parts supplied with the kit (especially gaskets) can result in poor performance later.

    Most carburetor rebuilding kits include specific procedures which should be followed during overhaul.

    Most carburetor manufacturers supply overhaul kits of these basic types: minor repair; major repair; and gasket kits. Basically, they contain the following:

    Minor Repair Kits:


    All gaskets
     
    Float needle valve
     
    Mixture adjusting screws
     
    All Diaphragms
     
    Spring for the pump diaphragm
     

    Major Repair Kits:


    All jets and gaskets
     
    All diaphragms
     
    Float needle valve
     
    Mixture adjusting screws
     
    Pump ball valve
     
    Main jet carrier
     
    Float
     
    Some float bowl cover holddown screws and washers
     

    Gasket Kits:


    All gaskets
     

    After cleaning and checking all components, reassemble the carburetor, using new parts and referring to the exploded view. When reassembling, make sure that all screws and jets are tight in their seats, but do not overtighten, as the tips will be distorted. Tighten all screws gradually, in rotation. Do not tighten needle valves into their seats; uneven jetting will result. Always use new gaskets. Be sure to adjust the float level.

    Click image to see an enlarged view

    Fig. Fig. 17: Exploded view of the Federal model Carter YFA 1-bbl carburetor



    Click image to see an enlarged view

    Fig. Fig. 18: Exploded view of the California model Carter YFA 1-bbl



    Click image to see an enlarged view

    Fig. Fig. 19: Exploded view of the Motorcraft 1910 2-bbl carburetor



    Click image to see an enlarged view

    Fig. Fig. 20: Carter YFA Carburetor Specifications



    Click image to see an enlarged view

    Fig. Fig. 21: Motorcraft 1910A Carburetor Specifications



    Click image to see an enlarged view

    Fig. Fig. 22: Aisan Model Y Carburetor Specifications

     
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