IF it's only firing one injector, then you should check for battery voltage on one side of the dead harness (not sure which color should be hot) with the key on. If there's voltage, then it's almost certainly your ECM. If it doesn't have voltage, then very carefully check your fuses and make sure there isn't an open circuit somewhere between the TBI and fuse panel.
Good Luck and God Bless
Good Luck and God Bless