Hello Gregte, Yes you can read how much fuel is in the tank with the a multimeter. I used to use one in my old Sunbird when my fuel gauge stopped working, I would measure the resistance in ohms, I'm not sure now what the readings were now but if you tap into the wires you will soon find out your full mark and when its empty. Mine was easy to get at I just kept a multimeter in the trunk, cause the sending unit was accessible. hope I helped.
