Are you sure it is not starting due to lack of fuel? You need to install pressure gauge and see what fuel pressure actually is. You may also be missing spark. Have you checked for this also?
On your 1990 Ford Festiva-Import 1.3L FI SOHC , the Relay - Fuel Pump is located:
Front seating area, driver side, under dash, above fuse panel, mounted on driver side of steering column