Installing a fuel guage

[james bernard]

After a bit of testing, I’ve come to the conclusion that my gas guage is bad In my 67 Polara. Does anyone have any tips on whats involved in chang it? Not sure if the dash would have to be removed? Just thought I’d put it out there before I start digging into it. Thanks!

 

[HWYCRZR]

If you have ruled out the sending unit and wiring then you will need to remove the instrument panel.
But before you do that, I have a few questions?
Does your temperature gauge work?
Edit. The 5 volt voltage regulator/ limiter is mounted on the back of the instrument panel. If the voltage limiter is burnt out neither your fuel or temperature gauge will work. If your temperature gauge works, then I would do a little more trouble shooting. Does the gauge move at all when you turn the key on? If no movement, it could be the gauge. However if your fuel sending wires are an open circuit it also may not move.

I also made a gauge tester using a potentiometer. 10 ohms resistance all gauges should read full. 23 ohms resistance should be 1/2 and 74 ohms should make the gauge read empty.

 

[HWYCRZR]

Where the arrow is pointing in the schematic to the voltage limiter you should have 12 volts (switched power). The terminal going to the fuel and temperature gauge should be 5 volts.

 

[james bernard]

Thank you very much for all the information! And yes. My temperature guage works fine. There is no movement at all when I hit the key. I replaced the sending unit a while back and no change. I’m kinda concerned about removing the instrument panel only because I’m worried I may open up can of worms. All that wiring that hasn’t been moved in 55 years. I don’t know. Should that be a concern in your opinion?

 

[HWYCRZR]

It can be a can of worms, but it could also give you an opportunity to clean things up. Be careful in pulling out the wire connection on the back of the dash. If you don’t have a service manual please download one at MyMopar
And read the instructions to remove the IP. There are no short cuts. Guarantee it will save you time and headaches.

Before pulling,test 1 more thing. It will only take a few minutes. Put a jumper wire on the back stud of the gauge that the dark blue wire (sending unit) eventually hooks to (G5-18-DBL in the schematic (not the one with the white tracer)). And not the one the 5 volt power is going to. Ideally you would hook a resistor inline and ground (10 -74 ohms). If you don’t have a resistor to go inline hook your ohmmeter to that stud and ground and see if you can read the resistance from your sending unit before it goes into the gauge. 1/2 a tank should be around 23 ohms full is 10 ohms and empty is 74. If you are not seeing any resistance you will need to back track the dark blue wire testing along the way to see where it may be faulty. In that case I would start at the sending unit test there, then the connector behind the side kick panel, then the gauge connector. if you have resistance it will be your gauge.

 

[1970FuryConv]

If you ground the sending unit wire and the gauge does not move:
*Sending unit wire does not have continuity to gauge
Or
*Gauge is bad
Or
*Gauge is getting no power from the voltage limiter

 

[HWYCRZR]

Agree with your points above with a small *. If I look at the schematic, if you are getting power to the temp gauge you should be getting power to your fuel gauge unless your Instrument panel circuit board is damaged. Either way after those tests and no gauge movement you will need to remove the panel and disassemble on your work bench where you can easily check out both.

Good luck

 

[John Kirby]

Ground the wire at the tank and see if the gauge moves. No movement indicates a wiring or gauge issue. Movement indicates the tank isn't grounded. You can make a ground strap from the frame to the tank. Connect it to the tank at the flange where the top and bottom are welded together. Just think about where your connecting, you don't want a gas leak.

 

[66furys]

I sent my gauges out for resto, but evidently the voltage limiter is bad, and company would not want to guarantee so did not try to repair. I am getting a VRC601 limiter to try to energize my mess. However, it seems a bit difficult to determine which terminal is input 12v, and which is 5 v out. From the wiring diagrams, it would appear that the ground, easy, is on one end, the 12V in is in the center, and the 5 V out is opposite the ground. Any thoughts on this thingie. I dont want to burn him up w/o some research. thanks

 

[66furys]

With more reading, I have found Big Johns point on the RTE regulator. And, they have some pretty good discussion and work that will help figure this out.

 

[3175375]

With more reading, I have found Big Johns point on the RTE regulator. And, they have some pretty good discussion and work that will help figure this out.

I have the RTE regulator and it is slow to finally get to the correct fuel level reading, but works as advertised.

 

[66furys]

appreciate it, thanks