ISUZU Amigo/Pick-ups/Rodeo/Trooper 1981-1996

Carburetors

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ADJUSTMENTS



Fast Idle

The automatic choke fast idle is adjusted by the opening angle of the throttle valve on the carburetor.

  1. Disconnect and plug the vacuum line to the distributor, idle compensator and EGR valve.
  2.  
  3. Adjust the throttle valve opening at the first step of the fast idle cam to 16° for manual transmissions or 18° for automatics.
  4.  
  5. Start the engine. The fast idle should be approximately 3200 rpm after the engine is warm.
  6.  
  7. Shut the engine off. Attach the vacuum lines disconnected earlier.
  8.  

Float Level

See Figure 1



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Fig. Fig. 1: Float level adjustment

  1. Remove the carburetor and float cover.
  2.  
  3. The fuel level is normal if it is within the mark on the window glass of the float chamber when the engine is stationary.
  4.  
  5. If the level is outside the line, make necessary adjustments by bending the float seat. The needle valve should have an effective stroke of about 0.059 in. (1.5mm). Check this measurement between the valve stem and the float seat.
  6.  

Do not bend the needle valve rod when installing the float.

  1. Install the float cover and carburetor.
  2.  

Primary Throttle Valve
EXCEPT 4ZD1 ENGINE

See Figure 2



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Fig. Fig. 2: Primary throttle valve adjustment

The primary throttle valve is opened by means of the fast idle adjusting screw to an angle of 16° when the choke valve is completely closed. The primary throttle valve opening angle may be checked as follows:

  1. Close the choke valve completely and measure the clearance between the center of the throttle valve and the wall of the throttle valve chamber. Standard clearance is 0.051-0.059 in. (1.3-1.5mm).
  2.  
  3. Adjust the throttle valve opening angle with the fast idle adjusting screw.
  4.  

Be sure to turn the throttle stop screw all the way in before measuring the clearance.

4ZD1 ENGINE

See Figure 3



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Fig. Fig. 3: Throttle valve adjustment

  1. Slowly open the primary throttle valve until the kick lever tang contacts the return plate.
  2.  
  3. Measure the clearance between the choke valve and the choke valve chamber wall.
  4.  
  5. If the clearance measured is not 0.27-0.33 in. (7.0-8.5mm), bend the kick lever tang to adjust.
  6.  

Kick Lever

See Figure 4



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Fig. Fig. 4: Kick lever adjustment

  1. Turn out the throttle valve adjusting screw to completely close the primary side of the throttle valve.
  2.  
  3. Loosen the locknut on the kick lever screw and turn the screw until it is in contact with the return plate.
  4.  
  5. Tighten the locknut.
  6.  

Choke Valve Opening
4ZD1 ENGINES

See Figure 5



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Fig. Fig. 5: Choke valve opening adjustment

  1. Move the fast idle screw tip against the 2nd step of the fast idle cam.
  2.  
  3. Measure the clearance between the choke valve and the choke valve chamber wall.
  4.  
  5. If the clearance measured is not 0.031-0.051 in. (0.8-1.3mm), bend the counter lever tang to adjust.
  6.  

Unloader
4ZD1 ENGINE

See Figure 6



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Fig. Fig. 6: Choke unloader adjustment

  1. Open the primary valve fully.
  2.  
  3. Measure the clearance between the choke valve and the choke valve chamber wall.
  4.  
  5. If the clearance measured is not 0.098-0.129 in. (2.5-3.3mm), bend the adjusting lever tang to adjust.
  6.  

REMOVAL & INSTALLATION



See Figure 7



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Fig. Fig. 7: Be sure to label the hoses before disconnecting them

  1. Disconnect the negative (-) battery cable.
  2.  
  3. Disconnect the PCV and AIR hoses.
  4.  
  5. Remove the air cleaner assembly with the vacuum hose and air duct.
  6.  
  7. Remove the throttle return spring.
  8.  
  9. Label and disconnect the emission control vacuum hoses.
  10.  
  11. Disconnect the lead wire connectors and accelerator cable.
  12.  
  13. Release the fuel pressure and disconnect the fuel pipes.
  14.  
  15. Remove the carburetor retaining nuts and carburetor.
  16.  
  17. Remove the old gasket.
  18.  

To install:
  1. Install the carburetor, new gaskets and retaining nuts.
  2.  
  3. Connect the fuel pipes.
  4.  
  5. Fasten the lead wire connectors and accelerator cable.
  6.  
  7. Connect the emission control vacuum hoses.
  8.  
  9. Install the throttle return spring.
  10.  
  11. Install the air cleaner assembly with the vacuum hose and air duct.
  12.  
  13. Connect the PCV and AIR hoses.
  14.  
  15. Connect the negative (-) battery cable, start the engine and check for leaks.
  16.  

OVERHAUL



Except 4ZD1 Engine

See Figure 8



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Fig. Fig. 8: Exploded view of the carburetor

DISASSEMBLY

When disassembling or reassembling the carburetor, use the proper tools. Keep the disassembled parts in separate groups, according to the systems from which they were removed, to avoid interchanging of parts. Clean all disassembled parts in carburetor cleaner and clean out orifices with compressed air.

  1. Remove the carburetor from the vehicle and clean the outside dirt using engine cleaner.
  2.  
  3. Disconnect the accelerator pump lever.
  4.  
  5. Disconnect the rubber hose from the slow actuator.
  6.  
  7. Remove the throttle return spring. Flatten the harness clips under the choke housing and remove the wires from the clips. Disconnect the choke wires.
  8.  
  9. Remove the fuel nipple and strainer.
  10.  
  11. Disconnect the choke connecting rod from the counter lever by removing the circlip.
  12.  
  13. Remove the choke chamber from the float chamber.
  14.  
  15. Remove the circlip between the diaphragm and secondary throttle lever. Loosen the three diaphragm chamber attaching screws, then remove the diaphragm assembly.
  16.  
  17. Separate the float chamber from the throttle body.
  18.  
  19. Remove the slow actuator and accelerator pump assembly.
  20.  
  21. Remove the float needle valve assembly.
  22.  
  23. Remove the main actuator, being careful not to damage the rubber seal or lose the float collar.
  24.  
  25. Disassemble the diaphragm chamber and check the diaphragm for damage.
  26.  
  27. Remove the jets from the upper part of the float chamber.
  28.  
  29. Remove the injector weight plug, weight, check ball and spring.
  30.  
  31. Remove the two main jet plugs and jets.
  32.  
  33. Remove the primary slow air bleed from the choke chamber.
  34.  

The screws retaining the primary throttle valve, secondary throttle valve and choke valve are carefully tightened and locked with threadlocking compound.

  1. Inspect all parts for cracks, deterioration and corrosion. Replace if necessary.
  2.  

ASSEMBLY

When reassembling the accelerator pump, fill the cylinder with fuel and check to be sure fuel is injected smoothly.

  1. Install the primary slow air bleed into the choke chamber.
  2.  
  3. Install the two main jets plugs and jets.
  4.  
  5. Install the injector spring, check ball, weight and weight plug.
  6.  
  7. Install the jets to the upper part of the float chamber.
  8.  
  9. Reassemble the diaphragm chamber.
  10.  
  11. Install the main actuator, being careful not to damage the rubber seal or lose the float collar.
  12.  
  13. Install the float needle valve assembly.
  14.  
  15. Install the slow actuator and accelerator pump assembly.
  16.  
  17. Install the float chamber to the throttle body and tighten the screws.
  18.  
  19. Install the circlip between the diaphragm and secondary throttle lever. Install the diaphragm assembly.
  20.  
  21. Install the choke chamber to the float chamber.
  22.  
  23. Attach the choke connecting rod to the counter lever and install the circlip.
  24.  
  25. Install the fuel nipple and strainer.
  26.  
  27. Install the throttle return spring. Connect the choke wires.
  28.  
  29. Connect the rubber hose to the slow actuator.
  30.  
  31. Connect the accelerator pump lever.
  32.  
  33. Install the carburetor to the vehicle, start the engine and check for leaks.
  34.  

4ZD1 Engine

See Figures 9, 10 and 11



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Fig. Fig. 9: Major component disassembly



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Fig. Fig. 10: Minor component assembly



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Fig. Fig. 11: Throttle chamber disassembly

DISASSEMBLY
  1. Remove the carburetor from the vehicle and clean the outside with engine cleaner.
  2.  

Major component disassembly:
  1. Remove the assist spring, pump rod split pin with washer, pump lever and split pin.
  2.  
  3. Remove the return spring and main spring.
  4.  
  5. Remove the slow cut solenoid, fast idler cam and spring.
  6.  
  7. Remove the choke chamber assembly.
  8.  
  9. Remove the throttle chamber screws and float chamber assembly from the throttle chamber.
  10.  

Minor component disassembly:
  1. Remove the vent cover and duty solenoid.
  2.  
  3. From the choke chamber, remove the fuel nipple, fuel filter and level gauge cover.
  4.  
  5. Remove the float and collar from the housing.
  6.  
  7. Remove the needle valve assembly.
  8.  
  9. Remove the secondary and primary main jets.
  10.  
  11. Remove the accelerator pump piston, pump cover, return spring and pump set screw.
  12.  
  13. Remove the injector spring, weight and taper plug.
  14.  
  15. Remove the slow jet spring, primary and secondary slow jets.
  16.  
  17. Remove the primary and secondary main air bleeds from the float chamber.
  18.  

Throttle chamber disassembly:

Do not disassemble the throttle chamber assembly unless damaged or not functioning properly. Clean and reassemble as a complete unit.

  1. Remove the diaphragm chamber cover, spring and diaphragm.
  2.  
  3. Remove the idler adjusting screw, throttle adjusting screw, throttle shaft nut and washer.
  4.  
  5. Remove the spring hanger and shaft collar.
  6.  
  7. Remove the fast idler adjusting lever and screw.
  8.  
  9. Remove the kick lever, return spring, return plate and sleeve.
  10.  
  11. Remove the adjusting lever from the throttle chamber.
  12.  

ASSEMBLY
If throttle chamber was disassembled:
  1. Install the kick lever, return spring, return plate and sleeve.
  2.  
  3. Install the fast idler adjusting lever and screw.
  4.  
  5. Install the spring hanger and shaft collar.
  6.  
  7. Install the idler adjusting screw, throttle adjusting screw and throttle shaft nut and washer.
  8.  
  9. Install the diaphragm, spring and diaphragm chamber cover.
  10.  

Minor component assembly:
  1. Install the primary and secondary main air bleeds to the float chamber.
  2.  
  3. Install the slow jet spring, primary and secondary slow jets.
  4.  
  5. Install the injector spring, weight and taper plug.
  6.  
  7. Install the accelerator pump piston, pump cover, return spring and pump set screw.
  8.  
  9. Install the secondary and primary main jets.
  10.  
  11. Install the needle valve assembly.
  12.  
  13. Install the float and collar to the housing.
  14.  
  15. To the choke chamber, install the level gauge cover, fuel filter and nipple.
  16.  
  17. Install the vent cover and duty solenoid.
  18.  
  19. Install the throttle chamber screws and float chamber assembly to the throttle chamber.
  20.  
  21. Install the choke chamber assembly.
  22.  
  23. Install the slow cut solenoid, fast idler cam and spring.
  24.  
  25. Install the return spring and main spring.
  26.  

Major component assembly:
  1. Install the assist spring, pump rod split pin with washer and pump lever and split pin.
  2.  
  3. Install the carburetor to the vehicle, with new gaskets. Start the engine and check for leaks.
  4.  

 
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