1. Open the hood of your Mustang GT.
2. Locate the relay box. It is typically a black plastic box with a cover. On the 1999 Mustang GT, it's usually mounted on the driver's side fender, near the battery.
3. Remove the cover of the relay box.
4. Inside the relay box, you'll find several relays. The fuel pump relay is usually labeled as "Fuel Pump" or "FP."
5. The fuel pump relay is typically a small black or gray box with four terminals.
6. Take note of the position of the fuel pump relay and carefully remove it from the relay box by gently pulling it upwards.
7. Once you have removed the fuel pump relay, you can inspect it for any damage or corrosion. If necessary, you can replace it with a new relay.
8. Reinstall the new (or old) fuel pump relay by aligning it with the terminals and gently pushing it down until it clicks into place.
9. Replace the cover of the relay box and close the hood of your Mustang GT.
You can consult the owner's manual or a vehicle-specific repair guide to confirm the exact location and procedure for accessing the fuel pump relay in your 1999 Ford Mustang GT.
