There is no sender unit fitted yet all my LED's light up showing the tanks full?

When you first connect the LED gauge and power it up and there is no sender unit in the tank wired to it, then all the LEDs will light up to show the tank is full.  You have not damaged the unit doing this.

This is not a fault it is a fail safe procedure we have designed into the LED to light up all the LED's should the wire from the tank sender be broken or before a sender unit is even fitted.

Fitting a sender unit in the tank to the LED will mean it then operates as normal.

All we suggest is that when all connection are made the LED unit is not powered up ( live )