GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1995 🢒 Blazer - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Central MFI Unit Replacement

Disassemble Procedure
  1. Disconnect the negative battery cable.
  2. Disconnect the plastic cover.
  3. Disconnect the wire harnesses, including
    4. • Throttle Position (TP) Sensor
    • Idle Air Control (IAC) Motor
    • Manifold Absolute Pressure (MAP) Sensor
    • Intake manifold tuning valve assembly
  4. Disconnect the throttle and cruise cable from the upper intake manifold.
  5. Disconnect the ignition coil.
  6. Disconnect the crankcase ventilation hose at the upper intake manifold.
  7. Disconnect the vacuum hoses at front and rear of upper intake manifold.
  8. Disconnect the air cleaner snorkel.
  9. Disconnect the upper intake manifold bolts and studs.

    10. Mark the location of all studs for proper reassembly.

    Important:  Do Not attempt to disassemble the Central MFI assembly, it is serviceable as an assembly.

  10. Disconnect the upper intake manifold. Refer to Fuel Pressure Relief Procedure before disconnecting the fuel lines.

Removal Procedure
  1. Remove the injector wiring harness connector at Central MFI assembly.
  2. Remove the fuel fitting clip and discard.
  3. Remove the fuel inlet and return tube and fitting assembly. Discard the O-ring seals.
  4. Remove the Central MFI assembly.
    5. • Squeeze the poppet nozzle locking tabs together while lifting nozzle out of casting socket.
    • After removing the six poppet nozzles, lift the Central MFI assembly out of casting.

Assemble Procedure
  1. Connect the Central MFI assembly.
    2. • Align the Central MFI assembly grommet with the casting grommet slots and push down until it is seated in bottom guide hole.
    • Push poppet nozzles into casting sockets.
    • Inspect the poppet nozzles they must be firmly seated and locked in casting sockets.
  2. Connect the fuel inlet and return tube and fitting assembly. Install the new O-ring seals coated with clean engine oil.

    3. Important: Test for fuel leakage. Pressurize fuel system, verify no fuel leakage at inlet and return tube to Central MFI unit.

  3. Connect the new fuel fitting clip.

Installation Procedure

    Object Number: 1576372 Size: MH
  1. Install the upper intake manifold gasket with green sealing lines facing up.
  2. Install the upper intake manifold.

    3. Use care not to pinch the injector wires between the upper and lower intake manifolds.

  3. Install the upper intake manifold bolts. Use the marks made at disassembly for proper stud location.

    4. Tighten
    Tighten the bolts to 10 N·m (88 lb in). Using the sequence shown.

  4. Install the crankcase ventilation hose to upper intake manifold.
  5. Install the vacuum hoses to front and rear of upper intake manifold.
  6. Install the throttle and cruise cable to upper intake manifold.
  7. Install the ignition coil.
  8. Install the air cleaner tube.
  9. Install the wiring harnesses, including:
    10. • Throttle Position (TP) sensor
    • Idle Air Control (IAC) motor
    • Manifold Absolute Pressure (MAP) sensor
    • Intake manifold tuning valve assembly.
  10. Install the plastic cover.