Over the last three weeks my fuel gauge will drop to empty and the low fuel light will come on. This does not happen at every start up, just once or twice every other day. It happens after I have driven about one mile. The gauge will show normal fuel level at start up, and then will drop to empty. Sometimes it will go back to normal fuel level when driving. The tank has fuel in it. The gauge will just act up for no reason. Where can I start looking to fix this problem?