temp gauge help please

[GT400]

i've been running a mechanical temp gauge on my car since i got it running, but finally fot the bug to fix the electric one. i read all the other threads i could find on the subject but still cant get it right. i tried the stock sensor, a new sensor, and a new supra sensor, and all three cause the gauge to jump straight to the top above H. any ideas?

Thanks,
Daniel

 

[sideshow]

u have not connected the earth from temp gauge
very common thing to do if yr not an expert in conversions on toyotas