Those wires are just extra ground for the battery...Fords need a lot of ground.
I doubt that's the reason you're not getting adequate power to your fuel pump. Your fuel pump (in tank, I assume) should have ground from the EEC, I believe? Your EEC ground is the little connector type thing right by the battery and starter solonoid.
I'd get a voltmeter and check voltages at the connector between inertia switch and fuel pump and work forward from there. Does the pump turn on at all?