Fuel pump relay location

If you are able to jump the relay, then there is power there. Are you sure you didn't get a bad ir the wrong relay? If the power is there, it should work.

Hi:
If you are getting fuel to the injectors, there must be a problem with the injection system itself. I am going to forward this problem to a friend who is much better at fuel injection than I am. He will get back with you ASAP.

Joe

You need to test fuel pressure in system also in the back of your car (hatch?) There is a small black grommet protecting a hole, inside that hole you can reach a reset button on your fuel pump. Maybe give that a whirl?
89 Mustang fuel relay

should be in the trunk on the drivers side, at some point Ford moved it to the fuse block at your left foot.

The fule pump relay is actually under the drive side seat. Its very unusal for a relay to go out unless you have a short some where. A commont problem in early 90 fords are relay harness connections and wiring components. Its more likley that the harness under the drive seat has a loose connection check by pulling the wires from the back of the harness lightly to see if they are loose. If they are secure and snug, trace the line under the carpet and it runs directly to the fuse box under your left foot if you are seated in the driver side chair.