Checked this last night, I have 0.5V at the connector behind the ECU and about the same at the relay, even though every other wire going in reads about 11.5v or higher...
Is the relay currently fitted a standard yellow Ford one?
Sounds like you need to try another relay. They're nothing special, so try another with the same pin out - there are 2 pin layout types (but watch the relay's current rating).
Check that the fuel pump earth at the back of the car looks solid.
Also checked the black/yellow wire at the dash, that reads 2.3ish volts. All 4 wires onto the ignition read 11.7V or higher.
The black/yellow wire comes from fuse 22. Pull the fuse and measure the voltage that feeds the fuse. If 12V, replace fuse with new one.