In need of electrical help

I am having an electrical problem. Going by the wiring diagram and hooking my gas/ temp gauge up when I turn the key on the gas gauge works but the temp gauge goes all the way to hot. I have changed some wires to hook up the temp gauge and it works but the gas gauge quits and goes all the way to full. What am I doing wrong?

First check that each gauge is getting about 5 volts. If they are getting 0 or 12v you might need to replace the constant voltage regulator. On a 65 mustang its a little box in the middle of the back of the gauge cluster. If you have to replace it, don't get the one from CJ Pony Parts. When that one fails it passes 12v which burns up some gauges. A good one should go to 0v when it fails. Since one of the gauges works and the other doesn't though, I doubt the regulator is the problem.

If you have 5v on one wire going to the temp gauge and 0v on the other (which you should), try running a new wire from the temp sending unit to the terminal on the gauge where the 0v wire would go. If that doesn't work, try replacing the temp sending unit. Or instead of just replacing the temp sending unit you might be able to test it by measuring the resistance from the terminal on the temp sending unit to ground when the engine is cold and then measuring the resistance as the engine warms up. It should change but I have no idea how much. Thats all I can think of.

could be a short (to +), check to make sure the insulation hasn't rubbed off or melted on any wires. i would start looking under the dash and at the firewall.

check continuity with a multimeter through the pink wire to the coil, and the wires to your gauges. that should tell you which wires are touching.

Thanks for the replys. I will now start to check the system out and see what is the problem. Atleast now I have somewhere to start. Thanks