www.fordcaprimania3000.com

Seems to me the only part of the circuit you have not checked is
where the earth wire actually earth's to the car body.
suspect bad earth connection at this point.
Unfortunately I don't know where this is
Anyone else have any ideas

If the wiring is the same as the 2.8 then the connection also goes off the fuse box....the upper 2 spade connectors...one is empty (on mine) the other one is the wiring going to the pump....the wire could be dodgy (mine was shorting on the bodywork) or the fuse is gone.....

will get a pic later

connect a bulb to the live and earth wires or a meter and check to see if there is power if no then check the contact at the fuse box and also try re earthing