The fuel pump relay location on a 1999 Ford F-150 is in the
underhood fuse box, also known as the Power Distribution Box (PDB). However,
it's not always clearly labeled. You'll likely need to consult your owner's manual or a wiring diagram specific to your truck's engine (4.2L, 4.6L, or 5.4L) to find the correct relay. The manual will show the layout of the fuse box and identify the relay.
The relay itself might be labeled as "Fuel Pump" or it might be identified by a number. The wiring diagram will be essential in this case.
