Hi. New to forum. I have never tried this before, but I am attempting to add a 2nd fuel gauge to an existing system that already has one fuel gauge, and there is one sender in the gas tank. The gauges both operate off 33 to 233k resistance. The sender is perfectly matched for both. The problem seems to be when both are connected to same sending unit, both gauges drop on the readings and it is incorrect. I have figured a work around by using a switch to choose which gauge to use, however, when I use this method, the original gauge has a built in warning system when fuel level is low, so it is triggered by the switch when using the added fuel gauge. The original gauge shows full, and when I add the other gauge, operating both at same time, the gauge drops to about 3/4 of a tank, and the new gauge reads about the same. I didn't realize when simply adding a measuring device to an existing system, it would change the resistance going to the original gauge, apparently. Is there any suggestions or fixes for this. These fuel senders are using a ground circuit return, so there is no power to them. Typical fuel senders use a rheostat, and ground circuit goes to gauge which measures the amount of resistance and gauge correlates amount of fuel based on that resistance reading. Any help greatly appreciated.