Been trying to get some responses on the Temp, Gas and Charging gauges. Replaced the voltage regulator for the panel and got the Gas gauge to move. However it basically rolls all the way to the right and off the grid when the car is started (then all the way back left when the engine is turned off which makes sense). This is better than the original do nothing and sit on the far left no matter what happens. However, what does this mean? Is the tank not properly isolated? I have the return line strap in place.

Any recommendations on how to troubleshoot this would be appreciated.

the temp gauge has never moved even after the new Voltage regulator. How do I determine if the gauge or the sending unit are at fault?

Thanks and happy new year to you all!

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I believe the temperature and fuel gauge needles actually indicate how much current flows through them; farther right indicates greater current. To set up this current, the voltage regulator provides a constant voltage (5 V) to the gauge, which is connected to ground (the chassis) via the sending unit (fuel tank float or temperature sensor). The needle of the gauge moves farther right if more current flows to ground through the sending unit. However, the amount of current depends on the sending unit's resistance (i=V/R; current=voltage/resistance), which in turn depends on how high the float is in the tank (higher float, lower resistance) or how hot the engine coolant is. Both of these gauges should always move to the far left when the ignition is off, because there can never be any current if there is no voltage. If your fuel gauge pegs right when the ignition is on, it sounds like the gauge may be shorted to ground (connected directly to ground, bypassing the sending unit). If your temp gauge stays left when the engine is warm, it indicates that the circuit is broken somewhere, either in the gauge itself, in the wiring, or in the sending unit. Somewhere there is a break that prevents current from flowing to ground.

for the fuel gauge sounds like you have short circuit for the tank sender or its wiring. A full tank sender shall be roughly 10 ohms (in between the tank terminal and tank body). With empty tank the sender resistance is apprx 72 ohms. What do your fuel gauge show if you leave the terminal open at the tank? Should show nothing = empty.

Try to ground the temperature sender wire to the cylinder head. This shall make your temperature gauge active showing hot, even going over the scale.

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1966 Dart. 170 cu.in. 200 rwhp.