My 2001 silverado has just been experiencing a fuel gauge problem such as this. I filled up a full tank of gas...the fuel gauge read full, no problems. The next day I was sitting at a light and immediately the gauge dropped to empty and low fuel light came on...seconds later it jumped back to full and the light went off. The truck remained running and responsive the whole time, but is this a sign of a failing sensor? It has happened 3 times so far recently.