Please what I say carefully. I have a 65 c10. It has a new wiring harness behind the dash. I redone the wiring harness under the hood. It has a new sender in the new gas tank. When I turn the key on or the engine is running the gas gauge only goes up to the first mark on the face and the temp gauge does the same. I unhooked the sender wire at the tank turned the key on it still only goes up to first mark instead of pegging out when the sender is unhooked. Any ideas what the problem is?? I have power at the fuse box which feeds the gauge until I plug in the wire feeding the sending unit then lose power at the fuse. I think the problem is affecting both gauges because they are acting the same. I have 5 gallons of gas in the tank