There isn't a readily accessible, easily identifiable "fuel cut-off switch" like you might find on some vehicles or equipment on a 1999 Mercury Cougar. Fuel delivery is controlled electronically through the fuel pump relay and the PCM (Powertrain Control Module). To stop the fuel flow, you would need to disconnect the fuel pump relay or potentially disable the PCM (though this is significantly more complicated and not recommended without specialized knowledge).
If you need to stop fuel flow in an emergency (like a fire), it's more effective to disconnect the battery negative terminal. This will cut power to all electrical systems, including the fuel pump.
Do not attempt to tamper with the fuel system yourself unless you are a qualified mechanic. Improperly working with fuel lines or the fuel pump can lead to serious injury or damage.
