This will help you test you gauge. If the Gauge works you can then test your sender by disconnecting it and then putting an ohm meter on it and check the resistance as you move the arm up and down. The resistance range is shown on the guide in the link<br /><br /> http://www.tflx.com/pdf/GAUWORK.pdf
You can also disconnect the sender wire at the sender post at the fuel tank and ground it.With the key on(Not Started), the gauge should go to full. If so, the sender is at fault. Ground it away from the gas tank.