Fuel Pressure Release
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1997 GMC Savana, 1997 GMC Pickup, 1997 Chevrolet Pickup, 1997 Chevrolet Chevy Van, and 1997 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect battery terminals. Loosen fuel tank cap to relieve tank pressure. When ignition is turned off, an internal constant bleed in injection unit relieves fuel system pressure. No further pressure relief is required.