AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Carter YFA Carburetor

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See Figure 1

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Fig. Fig. 1: Exploded view of the Carter YFA carburetor components

This carburetor is used on the 4-150.

ADJUSTMENT - Float and Fuel Level



See Figure 2

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Fig. Fig. 2: Measuring the float clearance on the Carter YFA carburetor

  1. Remove the top of the carburetor and the gasket.
  2.  
  3. Invert the carburetor top and check the clearance from the top of the float to the bottom edge of the air horn with a float level gauge. Hold the carburetor top at eye level when making the check. The float arm should be resting on the inlet needle pin. To adjust, bend the float arm. Do not bend the tab at the end of the arm! See the Carburetor Specifications chart for the correct clearance.
  4.  

Fast Idle Linkage See Figure 3

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Fig. Fig. 3: Location of the fast idle adjustment screw (1) on the Carter YFA carburetor

This adjustment is performed with the air cleaner removed.

  1. Run the engine to normal operating temperature. Connect a tachometer according to the maker's instructions.
  2.  
  3. Disconnect and plug the EGR valve vacuum hose.
  4.  
  5. Position the fast idle adjustment screw on the second stop of the fast idle cam with the transmission in neutral.
  6.  
  7. Adjust the fast idle speed to 2300 rpm for auto. trans. and 2000 rpm for man. trans.
  8.  
  9. Idle the engine and reconnect the EGR hose.
  10.  

Initial Choke Valve Clearance

  1. Position the fast idle screw on the top step of the fast idle cam.
  2.  
  3. Using a vacuum pump, seat the choke vacuum break.
  4.  
  5. Apply light closing pressure in the choke plate to position the plate as far closed as possible without forcing it.
  6.  
  7. Measure the distance between the air horn wall and the choke plate. If it is not that specified in the Carburetor Specifications Chart, bend the choke vacuum break link until it is.
  8.  

Choke Setting

Once the rivets and choke cover are removed, a choke cover retainer kit is necessary for assembly.

  1. Remove the rivets, retainers, choke cover and coil following the instructions found in the cover retainer kit.
  2.  
  3. Position the fast idle adjustment screw on the highest stop of the fast idle cam.
  4.  
  5. Push on the intermediate choke lever and close the choke plate.
  6.  
  7. Insert the proper plug gauge, 0.050-0.080 in. (1.27-2.032mm) for manual trans. and 0.85 in. (21.59mm) for automatic trans., in the hole adjacent to the coil lever. The edge of the lever should barely contact the plug gauge.
  8.  
  9. Bend the intermediate choke rod to adjust.
  10.  

Unloader

  1. Obtain a Carburetor Choke Angle Gauge tool #J-26701-A or its equivalent. Rotate the scale on the gauge until the 0 mark is opposite the pointer.
  2.  
  3. Close the choke plate completely and set the magnet squarely on top of it.
  4.  
  5. Rotate the bubble until it is centered.
  6.  
  7. Rotate the degree scale until the 32° mark is opposite the pointer. On carburetors with choke cover sticker number 70172 the setting is 19°.
  8.  
  9. Hold the primary throttle valve wide open.
  10.  
  11. Bend the throttle lever tang until the bubble is centered.
  12.  

Metering Rod See Figure 4

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Fig. Fig. 4: Adjusting the metering rod on the Carter YFA carburetor

  1. Remove the air horn and gasket.
  2.  
  3. Make sure that the idle speed adjustment screw allows the throttle plate to close tightly in the bore.
  4.  
  5. Press down on the top of the pump diaphragm shaft until it bottoms.
  6.  
  7. In this position, adjust the metering rod by turning the adjusting screw counterclockwise, until the metering rod lightly bottoms in the main metering jet.
  8.  
  9. Turn the adjusting screw 1 full turn more.
  10.  
  11. Install the air horn and gasket, and adjust the curb idle speed.
  12.  

See Figures 5 through 12

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Fig. Fig. 5: Carburetor Specification Charts



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Fig. Fig. 6: Carier YF



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Fig. Fig. 7: Carter YFA



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Fig. Fig. 8: Rochester 2SE/E2SE



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Fig. Fig. 9: Autolite/Motorcraft 2100



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Fig. Fig. 10: Motorcraft 2100/2150



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Fig. Fig. 11: Autolite 4350



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Fig. Fig. 12: Troubleshooting Basic Fuel Systems Problems

 
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