Bradster's Notebook:

Notes on CVU retrofitting: The prototype in the picture was just epoxied to the terminal board and the hole in the LM7805 heatsink tab was enlarged to facilitate the mounting screw. I DO NOT recommend this for a permanent installation. (to much physical stress on the little LM7805). 

I have been running a solid state CVU in my '65 Mustang Coupe without any problems (cleans up some of the electrical systems static too).

The diagram shows how to mount the LM7805 inside the metal CVU housing. 

Fuel Gauge & Sending Unit Test (from the "65 Ford Mustang/Comet/ Falcon Shop Manual)

1. Disconnect the wire from the fuel level sending unit and connect it to a "known good" sending unit.

2. Connect a jumper wire from the sending unit mounting plate to the car frame.

3. Raise the float arm to the upper stop, the instrument panel gauge should read full, lower the the float arm to the bottom stop, the gauge should now read empty.

4. If the gauge reads properly, the sending unit in the gas tank is defective.

5. If the gauge unit still indicates improperly or is erratic in it's operation, the gauge unit or wiring to the gauge unit (possibly CVU) is faulty.

1. You will need a three jumper wires (w/alligator clips) and two resistors (10-ohm, 78-ohm)

2. Remove the gauge cluster from the dash (you will need access to the gauge's terminals)

3. Clip one jumper wire from the body (ground) to your gauge assembly's metal backing plate

4. Remove the sender wire from it's terminal on the back of the Gauge  (Yellow/White for Fuel, Red/White for Temperature)

5. Clip a jumper wire to that terminal and to a 10-ohm resistor

6. Clip the remaining jumper wire from the remaining lead on the resistor to ground

7. Turn ignition key to "Run" position

8. The gauge should read "Full" (after about 15 seconds)

9. Repeat steps 4-6 using the 78-ohm resistor

10. The gauge should read "Empty" (after about 15 seconds)

11. If the Gauge does not read "Full/Empty"  correctly there is a problem inside the gauge, wiring to the gauge, OR or the CVU.

Temperature Gauge Test (from the "1965 Ford Mustang/Comet/Falcon" Shop Manual)

1. Start the engine and allow it to run until it has reached "normal operating temperature". (200-212)

2. Place a thermostat in the coolant in the radiator filler neck. The temperature should read close to the temperature range of the coolant thermostat that is used.

3. The gauge in the instrument panel should indicate within the "normal" band. (1/2 scale) 

4. If the gauge does not indicate, momentarily short the temperature sender unit terminal wire to ground (ignition switch ON)

5. If the gauge now indicates the sender unit is defective or it was not properly sealed to the engine.

6. If the gauge does not indicate, the gauge, the wires leading to the gauge, (or the CVU) are at fault.