Carburetor - Carter Yfa 1-bbl Ford Cab & Chassis Ranger

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during REMOVAL & INSTALLATION or OVERHAUL procedures

APPLICATION

FORD MOTOR CO. (CARTER) CARBURETOR NO.

IDENTIFICATION

A carburetor identification tag is attached to carburetor. Tag contains part number prefix and suffix, design change code (if any) and assembly date code (including year, month and day). To obtain replacement parts, it is necessary to know identification number prefix, suffix and, in some instances, the design change code.

Ford Motor Co. Carburetor Identification Tag Identification tag is attached to top of carburetor. Scheme 212

DESCRIPTION

Carter YFA and YFA Feedback carburetors are made up of 3 main assemblies, including the air horn, main body and throttle body. An adjustment limiting vacuum diaphragm type automatic choke with an electric assist choke cap is used.

The electric choke adds a high mileage economy application to the carburetor. The main body on some models contains a temperature compensated accelerator pump which has a thermostatic disc designed to open and close within a specified range.

The YFA Feedback carburetor differs from the YFA in its addition of a feedback solenoid attached to the air horn assembly. This solenoid is used to meter air into both the idle and main circuits for improved engine performance.

A Microprocessor Control Unit (MCU) senses various engine needs and supplies feedback fuel as required by forcing air into fuel bowl, and in turn, more fuel into carburetor air stream.

ADJUSTMENT

Note. For all on-vehicle adjustments not covered in this article, see appropriate TUNE-UP article.

FLOAT LEVEL

1. Remove air cleaner assembly. Remove air horn and gasket from top of carburetor. Turn air horn assembly upside-down. Measure distance between top of float at free end and gasket surface of air horn. NOTE: DO NOT apply pressure against needle when adjusting float.
2. Bend float arm as necessary to obtain correct clearance. DO NOT bend tab at end of float arm as this will stop float travel to bottom of fuel bowl when empty.
3. When adjustment is completed, reinstall air horn and new gasket. Start engine and check for fuel leaks. Install air cleaner.

Float Level Clearance Adjustment Float arm should rest gently on needle. Scheme 213

Scheme 214

1. Remove air cleaner, air horn and gasket from carburetor. Back out idle speed adjusting screw until throttle plate is tightly closed in throttle bore. Press down on end of pump diaphragm shaft until assembly bottoms.
2. While holding diaphragm assembly in this position, turn rod adjustment screw counterclockwise until metering rod gently bottoms in body casting. (Scheme 214) Turn metering rod adjustment screw clockwise exactly 1 turn for final adjustment. (Scheme 214): Metering Rod Adjustment Before adjusting, press down on pump diaphragm shaft.
3. Install air horn and new gasket on carburetor. Start engine and check for fuel leaks. Install air cleaner.

CHOKE UNLOADER (DECHOKE)

1. Remove air cleaner. Hold throttle valve in fully open position and press choke valve toward closed position. Measure clearance between lower edge of choke valve and air horn wall.
2. Adjust by bending arm on choke lever of throttle lever. (Scheme 215) Bend arm up to increase clearance or down (away from fast idle cam) to decrease clearance. Operate throttle to check for binding or clearance interference. Install air cleaner.

Choke Unloader (Dechoke) Adjustment Adjust by bending choke lever arm of throttle lever. Scheme 215

CHOKE PLATE PULL-OFF CLEARANCE

1. Remove air cleaner. Place fast idle speed screw on highest step of fast idle cam. Cover vent hole in back of vacuum diaphragm with tape (if equipped).
2. Attach vacuum pump to pull-off diaphragm and apply enough vacuum to activate motor. Apply light closing pressure on choke valve without forcing it.
3. Check clearance between lower edge of choke valve and air horn wall. To adjust, bend choke diaphragm link. (Scheme 216) Remove vacuum pump and install air cleaner.

Choke Plate Pull-Off Clearance Adjustment Bend lever toward piston to decrease clearance. Scheme 216

FAST IDLE CAM POSITION

Place fast idle speed screw on kickdown step of fast idle cam, against shoulder of highest step. (Scheme 217) Measure clearance between lower edge of choke valve and air horn wall. Adjust clearance as needed by bending fast idle cam link.

Fast Idle Cam Position Measure clearance between choke valve and air horn wall. Scheme 217

AUTOMATIC CHOKE

Note. Automatic choke is of tamper-proof design. Use this procedure if choke is damaged or when carburetor is rebuilt.

1. Choke housing is non-adjustable. Setting is fixed by an index plate located between carburetor and choke cover. Color of index plate indicates calibration setting.
2. To replace index plate, loosen choke thermostat cover. Remove 2 rivets and retaining screw. Separate cover from carburetor and exchange index plates. Replace cover. Install new rivets and screw.

Exploded View of Carter Model YFA 1-Barrel Feedback & High Altitude Carburetor (Non-Feedback YFA Similar). Scheme 218

Scheme 219

1. Remove carburetor from engine. Remove thermostatic spring housing assembly, spring housing gasket, index plate, choke over center spring (if equipped) and fast idle link. Remove EGR WOT dump valve and bracket. Remove front mounted solenoid and bracket (if equipped).
2. Remove choke pull-off link and motor retaining screws (2). Disconnect link and remove pull-off motor assembly. Disengage link from choke shaft lever.
3. Remove air horn assembly screws. Remove idle speed control unit (ISC) and bracket assembly. On feedback or high altitude models, remove feedback solenoid and bracket assembly.
4. On all models, lift air horn away from main body and remove gasket. Turn air horn upside-down and remove float pin, float and lever assembly. Turn air horn right-side-up and catch needle pin, spring and needle as they fall out. Remove needle seat and gasket.
5. Remove air cleaner bracket. Remove choke plate attaching screws. File staked (burred) ends if necessary and use new screws during reassembly. Remove choke plate from air horn. Remove choke link lever and attaching screw. On feedback models, slide out choke shaft.
6. On all models, remove spring retainer from mechanical fuel bowl vent flapper valve (if equipped). Remove vent shaft rod and spring and flapper valve. Note position of spring on rod for reassembly. Turn main body upside-down and catch accelerator pump check ball and weight.
7. On non-feedback models, remove fuel bowl lever retaining screw from end of throttle shaft. Remove spring washer, vent rod, actuating lever and "E" clip. On feedback models, remove 2 screws and washers holding throttle position sensor to throttle flange. Remove backing plate, drive bushing and washer.
8. On all models, loosen throttle shaft arm set screw. Remove arm and pump connector link. Remove fast idle cam and screw. Remove accelerator pump diaphragm housing screws. Remove accelerator pump discharge tube.
9. Lift out pump diaphragm assembly, pump lifter link and metering rod as an assembly. Remove lifter link seal. Disengage metering rod arm spring from metering rod.
10. Remove metering rod from rod arm assembly. For reassembly reference, note location of any washers used to shim either spring. Compress upper pump spring and remove spring retainer.
11. Remove upper spring, metering rod arm assembly and pump lifter link from pump diaphragm shaft. Compress pump diaphragm spring. Remove pump diaphragm spring retainer, spring and pump diaphragm assembly from pump diaphragm housing.
12. Using jet tool or screwdriver, remove metering rod jet and low speed jet. Remove screws and separate throttle body flange assembly from main body casting. Remove gasket.
13. Remove throttle plate retaining screws. File staked (burred) ends if necessary and use new screws at reassembly. Slide throttle shaft and lever assembly out of throttle body. Note location of ends of torsion spring on throttle shaft for reassembly reference.
14. Remove idle mixture screw adjustment limiting cap and cup as follows: Invert carburetor assembly and tape all vacuum and fuel connection openings. Using a hacksaw, saw a slot lengthwise through thickness of cup. (Scheme 219) Insert screwdriver in slot and spread outer cup enough to remove inner cap. (Scheme 219): Idle Mixture Screw Limiter Cap Removal Saw slot through thickness of cup.
15. After removing limiter cap, count number of turns to lightly seat needle. Record for reassembly reference. Remove mixture screw, spring and cup. Remove wire harness bracket (if equipped).

CLEANING & INSPECTION

1. DO NOT immerse air horn in any solvent. Damage to vent shaft seal could result.
2. Use a regular carburetor cleaning solution. Soak components long enough to thoroughly clean all surfaces and passages of foreign matter.
3. DO NOT soak any components containing plastic, rubber or leather.
4. Remove any residue after cleaning by rinsing components in a suitable solvent.
5. Blow out all passages with compressed air.

REASSEMBLY

Note. Use new gaskets. Make sure that new gaskets fit correctly and that all holes and slots are punched through and correctly located.

Reverse disassembly procedures to reassemble carburetor, noting the following

1. If throttle valve was removed, make sure notch in valve is aligned with slotted idle port in throttle body flange. Throttle valve screws should be snug (not tight). Make sure throttle plate does not bind or stick. Restake or peen throttle plate screws.
2. When installing idle mixture screw, turn in until lightly seated, then back out number of turns recorded during disassembly. Make sure vacuum passage in accelerator pump housing is aligned with vacuum passage in main body.
3. Use Loctite on throttle position sensor retaining screws. When installing air horn on main body, ensure that bowl vent lever engages forked actuating lever (if equipped).

SPECIFICATIONS

CARBURETOR ADJUSTMENT SPECIFICATIONS