[MOTORHEAD]

If its .5 or.6 ohms from sender to ground, it's shorted .
I assume you moved the float arm up & down while watching the meter?
The coil thingy is the resistor winding part of it, and the piece that moves over the coil when the float arm is moved, is the wiper arm. The sender wire is connected to the wiper arm. Check continuity between sender terminal and wiper arm. Should be low or 0 ohms. Check resistance of windings (resistor) from one end to the other. Should read 70-100 ohms. One end of resistor should be connected to ground. Ck with ohmeter. Other end should be open (not connected to anything) As the float moves, the wiper arm makes contact with a changing number of windings to ground, thus varying the resistence to ground measured at the sender terminal. Try these cks and see what you get.