Check the brown wire that goes to the inertia switch then see if inertia switch has power on both sides it could be just a bad switch. It could also be a bad relay as well. If no power coming out of brown wire at relay try replacing it with a like relay and see if it works. It can also be a bad ground on fuel pump. I am assuming this has dual tanks so it could also be the tanks switch I am sending that along on how to check for that.
LH Side Of Engine Compartment, On Relay Bracket. Fuel pump relay is next to the EEC Relay.
Applicable to: 7.5L/V8-460
Check out the diagrams (Below). Please let us know what you find.
Images (Click to enlarge)
Monday, February 16th, 2015 AT 8:45 AM