Check for fuel leaks in engine compartment, fuel lines, and at tank. To reset inertia switch, turn ignition off. On Bronco and "F" series, switch location is on left kick panel, near emergency brake pedal.
On "E" series, switch location is passenger's side cowl panel, forward of right front door. Aerostar inertia switch is located in the right kick panel. Inertia switch location on Bronco II and Ranger is on floorboard to right of transmission hump. If inertia switch has been tripped, switch must be reset before vehicle can be restarted. Engine will run until residual fuel is exhausted. If vehicle is involved in a collision, inertia switch will stop fuel flow. EEC module operates fuel pump relay to provide fuel for starting engine while cranking.
When ignition switch is turned to "START" position. This circuit provides for pre-pressurization of fuel system. Opening ground circuit of fuel pump relay de-energizes fuel pump. If ignition is not turned on within one second, timing device in EEC module will create an open ground circuit. Fuel pump runs through contacts of fuel pump relay. Power is provided to both fuel pump relay and timing device in EEC module. When ignition is turned on, EEC power relay is energized, closing its contacts. Here is a guide to help you test the wiring in the system it sounds like you have a open wire or connection.