Engine Controls - Remove/install/overhaul Subaru XT I

INTRODUCTION

Removal, overhaul and installation procedures (when given by manufacturer) are covered in this article. If component removal and installation is primarily an unbolt and bolt-on procedure, only a torque specification may be furnished.

DISTRIBUTOR

Note. Overhaul procedure for XT and XT6 is not available from manufacturer. (Scheme 6)or (Scheme 7) for exploded view of Justy distributor.

Scheme 1

Scheme 2

CARBURETOR OVERHAUL

Note. Keep disassembled parts in appropriate order for reassembly reference.

Disassembly

1. Remove throttle return spring. Remove pump lever shaft screw, pump lever, washer and spring washer. Separate accelerator pump connecting rod and pump lever. Remove cam connecting rod, cotter pin and washer.
2. Disconnect vacuum hose from idle-up diaphragm. Remove choke chamber and gasket from air horn. Remove piston return spring, ball and injector weight from choke chamber. Remove anti-dieseling solenoid and spring.
3. Remove secondary diaphragm rod from secondary throttle valve shaft. Remove main body, throttle body and gasket. Carefully remove longest screw as it has a vacuum passage hole.
4. Remove accelerator pump piston and pump cover. Remove float shaft and needle valve assembly. Disconnect lead wires of duty solenoid valve from carburetor. Remove primary slow air bleed, secondary slow air bleed, switch vent solenoid valve and "O" ring.
5. Remove primary main air bleed, secondary main air bleed, primary plug and primary slow jet. Remove secondary slow jet, lock plate, float chamber drain plugs, primary and secondary main jets. Remove idle adjusting screw and spring. Remove nut and throttle valve shaft assembly. Remove throttle adjusting screw and spring.

Note. DO NOT immerse synthetic parts, electrical components or diaphragm assemblies in carburetor cleaner.

Cleaning

Clean cast parts with carburetor cleaner. Clean jets, fuel passages and vacuum ports with compressed air. DO NOT use wire or pointed metal objects. Clean all other parts with solvent and soft brush.

Inspection

1. Inspect air horn, throttle body and main body for cracks, nicks or burrs on gasket surfaces. Inspect float for damage. Inspect needle valve for wear or improper seating, and inspect seat strainer for rust or breaks.
2. Inspect jets and air bleeds for clogged orifices or damaged threads. Inspect accelerator pump piston assembly for wear on sliding portion and leather cup. Check spring for rust. Inspect secondary diaphragm for wear or damage. Check throttle valves for smooth movement and shaft wear.
3. Check diaphragm assemblies for leaks and proper operation. Apply battery voltage to terminals of solenoid valves and electric switches. Listen for operating sound as terminals are connected and disconnected.

Reassembly

To reassemble, reverse disassembly procedure. Use new gaskets. DO NOT mistake primary and secondary barrel parts. Install piston return spring with hook facing downward.

Note. For all on-vehicle adjustment procedures not covered in this article, see ADJUSTMENTS article.

Note. If fuel is not within mark on float chamber sight glass with engine idling, remove air horn and adjust using following procedures.

Float Level Adjustment

Invert air horn. Let float hang by its own weight and measure distance between float and air horn gasket surface (gasket removed). If necessary, bend tab "A" to adjust. (Scheme 1) Refer to the CARBURETOR ADJUSTMENT SPECIFICATIONS table.

Scheme 3

Float Drop Adjustment

After checking float level, gently lift float until float stop contacts air horn projection. Hold float in this position. Measure clearance between float tab and needle valve. Adjust by bending float stop. See CARBURETOR ADJUSTMENT SPECIFICATIONS table. (Scheme 2)

Scheme 4

Fast Idle Bench Adjustment

Close choke valve. Position fast idle lever on first (high) step of fast idle cam. Measure clearance between primary throttle valve and wall of throttle chamber. (Scheme 3) Refer to the CARBURETOR ADJUSTMENT SPECIFICATIONS table. If value is not as specified in table, adjust using fast idle speed adjusting screw.

Scheme 5

Vacuum Break Adjustment

1. Hold choke valve closed and move throttle lever. Release choke valve and ensure it is fully closed. With choke valve closed, apply vacuum to vacuum break diaphragm until diaphragm shaft moves.
2. Measure distance while lightly holding choke valve with hand. (Scheme 4) If clearance is not to specification, adjust by bending pawl at tip of lever. See «CARBURETOR ADJUSTMENT SPECIFICATIONS»(/subaru/xt/i-1987-1992/remont/removal-installation/#engine-controls-removeinstalloverhaul) table.

Scheme 6

Secondary Throttle Clearance Adjustment

Secondary throttle valve starts to open when primary throttle valve opens 43 degrees. As secondary throttle valve begins to open, measure clearance between primary throttle valve and wall of throttle chamber. Clearance should be.236" (6.0 mm). Rotate adjust plate to adjust as necessary. (Scheme 5)

Scheme 7

CARBURETOR ADJUSTMENT SPECIFICATIONS

FUEL PUMP

Note. Fuel system is pressurized. Before removing hose, filter, pump, etc., be sure to release fuel pressure. First disconnect wiring connector of fuel pump, then crank engine for more than 5 seconds. If engine starts, let engine run until it stops.

Removal

Release fuel system pressure, see NOTE above. Keep pump harness connector disconnected. Jack up vehicle. Clamp middle portion of thick hose connecting pipe (coupling) and pump. Prevent fuel from flowing out of fuel tank.

Loosen hose clamp, and disconnect hose. Remove three pump bracket mounting bolts, and remove pump together with pump damper.

Scheme 8

Connect leads to harness connector, and apply a 12-volt power supply to check whether pump operates.

Installation

If pump and damper have been removed from pump bracket, ensure mounting bolts are properly tightened. Install hose. Install pump bracket in position to vehicle body, and secure it with bolts. Use care not to drop spaceer of cushion rubber. Install hose. Connect pump harness connector. Run pump and check for fuel leaks.

Removal & Installation

Remove injector cap and gasket. Hold injector using pliers. Pull out injector from chamber assembly. Remove injector and "O" ring from chamber assembly. DO NOT damage nozzle on injector point. To install, reverse removal procedure.

If exhaust sensor is difficult to remove, use rust penetrant to avoid damaging exhaust threads.

If old sensor is reused, apply anti-seize compound to sensor threads. Ensure to keep anti-seize compound away from sensor body. New sensor are precoated with anti-seize compound. DO NOT remove anti-seize compound from sensor. Tighten to 18-25 ft. lbs. (24.4-33.9 N.m).

Remove throttle position sensor-to-throttle chamber screws (2). Remove throttle position sensor by pulling it in axial direction of throttle shaft. Note "O" ring attached to the throttle sensor mounting face of throttle chamber. To install, reverse removal procedure.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• CARBURETOR ADJUSTMENT SPECIFICATIONS