There was a recent post about IVR and someone posted a photo of the in fuel gauge IVR. your IVR could be stuck in the closed position supplying 12V to the gauges. do as Redfish said, with the fuel gauge sender (at the tank) disconnected turn key on for a short period of time and see what the fuel gauge does. if it stays at empty I would be looking into the internal IVR in your fuel gauge / resistance in the fuel gauge wiring / sender. the other gauges work the same high numerical resistance ~70-80 ohms or higher = empty, low temp and low oil pressure too. low resistance ~10 ohms should read full, hot and high oil pressure.