Not to sure about the fuel pump location on Fiesta's, if it's gravity fed like the Cosworths it will be in a cradle fitted underneath the tank, if not I guess it will be in the tank try.

If it's the latter if I were you I would check that it's deffo not the relay and measure the output on the wiring up to the tank if so this would indicate fuel pump fault.

Otherwise you won't be best happy if the fuel pump is ok and your got a fuel tank to re assemble and re fuel

Kind regards,

Martin.