I used the wiring diagram from the VDO site. 12v into +, grd to (-) side and G to sender pole. Used the (-) to ground to the sender case as well. Heated the sender in boiling water. Made the connections but the gauge did not register.

I made a similar hookup to the dual pole pressure sender. Made up a pressure chamber by using a brass "T" with air compressor into one fitting, mechanical pressure gauge in another fitting and the sender into the last fitting. 12v to + side of gauge, "G" of gauge to "G" of sender and ground to neg terminal of 12v supply and case of sender. Turn compresser on to 30psi but no registaring of the VDO gauge.
Does anyone know where I went wrong?
Thanks,
L. McC