Everything is 6 volt and I don't believe I have any damaged equipment. Last night I did go out and ground the sending unit. It read 1/2 full. I thought that sounds about right. I filled it up and it reads 3/4 - 7/8 full. Either I have a faulty gauge and/or sending unit. I think my next try is to measure the resistance on the sending unit while the tank is full. If that checks out, I may try adjusting the float.