Ok step one, unplug that resistor thing bolted to the subframe, follow the yellow wires up and you'll find a connector near/under the airbox. No need for it to pass the MOT and will need to be removed if you ever decide to fit one o' them uprated headlight looms

If you have a Digi MK2 then I think you've fried the ECU, especially if the pump just runs continuously instead of priming.
If its a pre-90 I may have one if you need it but I can't confirm if it works as I nabbed it off a car in the scrappy, you live anywhere near Bracknell?
When you refit the main earth lead, clean both the connector & box with a wire brush till its proper shiny else you'll never get a good contact and just fry the next ECU, and the next, and the next etc
