Inertia Fuel Shutoff (IFS) Switch
WARNING: This page is about a different car, the 1994 Mazda B3000 and 1994 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
See INERTIA FUEL SHUTOFF (IFS) SWITCH under ENGINE SENSORS & SWITCHES. Also see FUEL PRESSURE under FUEL SYSTEM in BASIC TESTING article in the ENGINE PERFORMANCE section.