I made an injector kill switch today using the injector fuse and a relay.
... but when I hooked the battery back up and started the car, the Ultragauge wasn't working.
... Turned out to be the interior light fuse was loose, ultra gauge working now.
... The car wont start if the switch is off and the engine turning. Have to reset by tuning ignition off and on, so much for coasting with the engine engaged and fuel off.