Fuel gauge / sender unit

Hi all I'm having trouble getting the fuel gauge working.. ..I've tried 3 sender units and 3 different sets of clocks .all the sender units look the same how ever one set of clocks are slightly different (top set in photo) and this one seemed to work at first but now nothing....as for the other set (bottom photo)
Every time you turn the ignition on the gauge shoots round to maximum ???? Can anyone help thanks Dom

Have a read of that dude

Sounds like you have a short to ground somewhere between the gauge and the sender.

In mine, the sender wire was trapped and shorted where it exited the firewall from the fuel tank compartment.

You can test the sender and the gauge separately, and the wiring in-between:
- Disconnect the sender wire from the sender unit, then between the spade terminal on the sender to ground should read from about 80 ohms (tank empty) to about 2 ohms (tank full).
- Disconnect the sender wire from the gauge then with ignition ON there should be 12V on both terminals on the gauge.
- With battery disconnected (so you don't blow up your meter) the sender wire (with nothing connected on either end) should be open-circuit to ground.

HTH