1995 Disco 1 fuel pump not coming on???

1995 disco fuel pump is not coming on when i turn key.(i can not hear it and no fuel in fuel rail) i have traced out wire harnes and everything looks ok. i have also replaced fuel pump and injectors and removed gas tank to clean spottless. i also hear fuel pump relay clicking when i turn key on. how do you know if fuel injector ecu is bad? i have also tried pushing reset button on fuel inertia switch. is the button supposed to stay pressed in when you push? the buttton on mine does not!!! Any way please help just rebuilt my 3.9 engine!!! thanks patrick brittingham:eek: