Yes, the fuel sending units are under those two covers. Just remove the four screws that hold each cover in place and remove them to gain access to the fuel sending units leads. The left side will have one plug, which is wired in series with the fuel sending unit on the right side, which will have two seperate plugs. On the right side, one plug is for the fuel pump and the other is for the fuel sending unit.
My guess is that the connection broke off from one of your fuel sending units. That's what happened to me. To test it, use an ohm meter. To fix it, remove the fuel pump/sending unit combo and solder the wire back to its lead. After that, reset the fuel gauge by testing the gauges (holding in the odometer trip reset button, then turning the key to the on position- keep holding the odometer button in until you see the gauges go up and back).