Instrument Constant Voltage Regulator Troubleshooting and Solid State Replacement 

Exactly, thats how Mechanical Bi metal Voltage regulators are designed to work. It's a Duty Cycle square wave output. It's effective Voltage is as you say ~ 5 - 6 volts. I agree w/ you , the Voltage regulator was probably NOT the problem. Thanks.

Thanks man. I'm glad to see your channel is doing well!

@@mechtrician1 thank you! Looks like you're still growing as well. Almost 1000 subs!

@@AlfsMustangGarage never imagined that would happen. Wasn’t even trying lol. Just wanted to document things.

@@mechtrician1 yup same here. If you build it, they will come right?

Pretty much, yes you can. There are some things I have found though that just aren’t worth my time anymore. It was more cost and time effective to just buy it.

Yes your falcon should use the same unit. From what I have seen, this unit was used on multiple ford and mercury vehicles throughout the 60s and I believe into the early 70s at least.

It wont have a CVR like this, however what you are describing sounds like the alternator or voltage regulator which is part of the alternator.

Literally cover that in this video.

@@mechtrician1 yessir, I saw that. Thank you!

This is strictly for the gauges.

Well a few things here. Sounds like separate issues but they may be related. For the first issue with fuel reading high and temp reading low, it could be a multitude of things, but probably not the CVR. Temp reading low could be the sending unit as could also be your issue with the fuel sending unit. Could be the gauges themselves as well since they are mechanical as well. It's difficult to say without some troubleshooting, but if they are not having a common problem, it probably isn't a common issue. The second issue may be related to the first though. Besides a bad ground which can cause current flows to bypass through the instrument circuit when things like headlights are on, it could be that the overall voltage goes up from the system voltage regulator on the car when the demand goes up. That would explain the gauges reading higher when load is higher. A test you can run is to check the system voltage (with the car running) with the headlights off, then check it with them on. If the voltage goes up quite a bit when they are on, then you know its related. Now the CVR is supposed to regulate this, but it only will to a point. If you still have the mechanical system voltage regulator, it can cause this. I found mine to be putting out almost 16V sometimes. I replaced it with a solid state one which is much more reliable (until I replaced the alternator with an internally regulated one, which is even more stable).

I have a solid state one on it now. Nothing changed. I replaced my original alternator with a Ford 3G. Nothing changed. I tested the temp lead where it connects to the engine. It showed 5 volts without the lights on and 9 volts with the lights on. So there's definitely more voltage coming out of the cvr with the lights on. As I'm sure you know, each gauge grounds its self through the sending unit and the cvr has its own separate ground. So there's no common ground that would effect all of them. It's a mystery.

I think I'll run a new, separate ground to the cvr and see what that does. Right now it disappears into the harness and converges with other ground wires, and they all connect to ground somewhere that I'm unable to locate.

That's interesting, the voltage bump says it though, that would be the issue. I would love to troubleshoot it. Probably try isolating its power source by interrupting its normal feed at the CVR, and substituting directly from the battery, and see if it goes away or not. Also, I'd trace the power feed and see what can influence it in the circuit. I have the schematic and will take a look.

Thanks. I've never thought of feeding it straight from the battery. I'm going to give that a shot.

It could but your temperature and oil pressure gauges would also read high too if you have them. If it’s just the fuel gauge it’s likely the sending unit or gauge itself.