Removal (4.3L)

Turn ignition off. Disconnect negative battery cable. Remove distributor. See DISTRIBUTOR .
Disconnect breather tube at air cleaner outlet duct. Disconnect Intake Air Temperature (IAT) sensor harness connector. Remove air cleaner outlet duct retaining wingnut. Loosen air cleaner outlet duct-to-MAF sensor clamp. Remove air cleaner outlet duct.
Release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEMS. Disconnect fuel feed and fuel return line fittings at rear of engine. See Fig 1. It may be necessary to loosen or remove fuel line bracket-to-cylinder head bolt to allow enough movement of fuel lines for access to knock sensor.
Disconnect knock sensor harness connector. Remove knock sensor retaining bolt and knock sensor. See Fig 2.

Fig 1: Locating Fuel Line Fittings & Fuel Line Bracket (4.3L)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Removing Knock Sensor

Courtesy of GENERAL MOTORS CORP.