Engine Controls - Remove/install/overhaul - 7.4L: Overhaul

Engine Controls - Remove/install/overhaul - 7.4L: Overhaul GMC C3500 HD

Disassembly (Fuel Meter Assembly Model 220)

Place throttle body on Holding Fixture (J-9789-118 or BT-30-15) to prevent damage to throttle valve. Remove fuel meter cover assembly-to-fuel meter body screws (note location of short screw). (Scheme 10) Remove fuel meter cover assembly. Remove and discard pressure regulator dust seal. Fuel meter cover assembly and pressure regulator are serviced as an assembly. DO NOT remove pressure regulator from cover assembly.
Remove fuel injectors. Note location of fuel inlet and outlet nuts and remove. Discard gaskets. Remove fuel meter body assembly-to-throttle body screws. (Scheme 10) Remove fuel meter body assembly. Remove and discard fuel meter body assembly gasket and fuel meter outlet gasket.
Remove TP sensor, IAC valve, ISC actuator, rubber components and gaskets. Clean all remaining (metal) parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air. Inspect mating surfaces for damage which may prevent gasket sealing. Repair or replace faulty components.

Place throttle body on Holding Fixture (J-9789-118 or BT-30-15) to prevent damage to throttle valve. Remove fuel meter body cover screws and remove fuel meter body cover. see scheme 4 If fuel pres sure regulator cover is removed, regulator diaphragm must be replaced to prevent fuel leaks.
Remove fuel injectors. Note location of fuel inlet and outlet nuts and remove. Discard gaskets and "O" rings. Remove fuel meter body assembly-to-throttle body screws. see scheme 4 Remove fuel meter body assembly. Remove and discard fuel meter body assembly gasket.
Remove TP sensor, IAC valve, fuel pressure regulator, governor drive motor and governor throttle drive assembly, lever and bearing assembly, rubber components, gaskets and diaphragms. Clean all remaining (metal) parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air. Inspect mating surfaces for damage which may prevent gasket sealing. Repair or replace faulty components.

On TBI 220, install NEW pressure regulator dust seal into recess of throttle body. Install NEW fuel meter outlet gasket on fuel meter body assembly. On all models, install NEW fuel meter body gasket on throttle body. Install TP sensor, IAC valve, rubber components, gaskets and diaphragms (if equipped).
On TBI 220, install ISC actuator. On TBI 295, install governor drive motor and governor throttle drive assembly, lever and bearing assembly, and fuel pressure regulator. On all models, install fuel meter body assembly onto throttle body. Apply thread locking compound (Loctite 262) to fuel meter body assembly screws and tighten to specification. See «TORQUE SPECIFICATIONS»(ref-20115-S16134245232001010200000) .
Lubricate fuel inlet and outlet "O" rings with clean engine oil. Install fuel inlet and outlet "O" rings, gaskets and nuts. Install fuel injectors. On TBI 220, install fuel meter cover assembly. On TBI 295, install fuel meter body cover. On all models, apply thread locking compound (Loctite 262) to cover attaching screws. Tighten screws.

Hold throttle cam lever open at 11 o'clock position. (Scheme 12) Remove mounting screws and remove governor drive motor. Release spring tension from governor drive lever. No other disassembly is possible.
If necessary, apply Special Grease (available in repair kit only) to governor mechanism. Align governor drive motor with cover plate. (Scheme 13) Reattach spring to governor drive lever.
Hold throttle cam lever open at 11 o'clock position. (Scheme 12) Tilt governor drive motor slightly. Ensure governor drive lever clears cover and align mounting holes. Apply Loctite to threads and tighten mounting screws to 27 INCH lbs. (3 N.m).
Rotate governor drive lever clockwise. Spring tension should be felt. Release lever. Governor drive lever should return to park position. If governor drive lever does not operate as described, recheck assembly procedure.

Disassembly procedure is not available from manufacturer. For disassembly, use exploded views of distributors. (Scheme 14)
When reassembling, ensure pick-up assembly arm is correctly installed on pin. If not, arm can float and cause ignition timing to vary. To prevent corrosion, lubricate terminals with petroleum jelly before installation.
To prevent heat damage, coat bottom of module and module rest pad in distributor housing with silicone grease. Before installing roll pin in driven gear, ensure timing mark on roll pin and rotor tip align. (Scheme 14)