If you're experiencing fuel-related problems (e.g., the car won't start, the engine is stalling), the issue is likely elsewhere in the fuel system, such as:
* Fuel pump: A faulty fuel pump is a common culprit.
* Fuel filter: A clogged fuel filter can restrict fuel flow.
* Fuel injectors: Problems with the injectors can prevent proper fuel delivery.
* Relay or fuse: A blown fuse or malfunctioning relay related to the fuel pump could interrupt power.
* Computer/ECM issue: A problem with the car's computer could be affecting fuel delivery.
Instead of looking for a nonexistent shutoff switch, you should troubleshoot these potential problems. Check your owner's manual for fuse box locations and diagrams. If you're not comfortable doing this yourself, take your Mustang to a qualified mechanic for diagnosis and repair.