Fuel gauge

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johnnycuda

johnnycuda

JohnnyCuda's 68
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68 Barracuda Guel gauge,
So usually for the last few cars,I take the wire off the sending unit back by the fuel tank ground it and the gauge goes to full. It’s usually the sending unit every time.
On this particular car, I did the same same test with no change? Gauge?
This is a picture of the back of my gauge Panel.
I noticed a condenser wire off. Does anybody know which plug it may go on and will it make a difference?

IMG_5900.jpeg
 
It will not keep the gauge from working if it's off.

As to which pin there was another post in the last couple of weeks that asked the same question.

My questions ..

  1. Do your oil and temp gauges work?
  2. If not most likely the IVR in the fuel gauge has failed.
 
The condenser is a radio noise filter, as the IVR or regulator is INSIDE the gas gauge on a Rally dash. It goes on the +12 stud

If you have not, I would eliminate the gauge wire as a possibility. Supply 12V power to the proper cluster pin, and ground, and ground the sender wire. Get the wire codes from the manual, follow them to the cluster connector, and follow the board traces to the gauge pins. Not that hard. One is 12V IN to the IVR, one pin is 5V OUT of the gauge which jumpers to the other gauges to supply them, and the 3rd is the sender
 
Also check your sender wire for continuity from front to back. Unplug it from the sender and the instrument cluster, then check for continuity to see if the wire is cracked or broken. 50+ year old wiring usually has not aged well.
 
67Dart273 said:
The condenser is a radio noise filter, as the IVR or regulator is INSIDE the gas gauge on a Rally dash. It goes on the +12 stud

If you have not, I would eliminate the gauge wire as a possibility. Supply 12V power to the proper cluster pin, and ground, and ground the sender wire. Get the wire codes from the manual, follow them to the cluster connector, and follow the board traces to the gauge pins. Not that hard. One is 12V IN to the IVR, one pin is 5V OUT of the gauge which jumpers to the other gauges to supply them, and the 3rd is the sender
Click to expand...
Beat me to it- another way of accomplishing the same thing.
 
A test light or meter is your friend here. Since you have the cluster loose, check for 12V power at the input side of the fuel gauge, then the 5v output terminal (it should pulse if your IVR is stock), then the sender terminal. I like using a test light that has a bit of resistance in it. That will make the gauge move if you have the correct power on the other two terminals and the gauge is working correctly. You can also ground that terminal for a second or two to do the same thing. Just don't let the needle peg to full as it might burn out. If all that works, the problem is in your sender wiring or test procedure for the sender.
 
Dana67Dart said:
It will not keep the gauge from working if it's off.

As to which pin there was another post in the last couple of weeks that asked the same question.

My questions ..

  1. Do your oil and temp gauges work?
  2. If not most likely the IVR in the fuel gauge has failed.
Click to expand...
Yes, my oil and temp gauge work fine, it’s just the fuel gauge.
As far as testing continuity, I think it’s the purple wire do I pull that bulkhead off on the back of the gauge? I don’t wanna break it. The wiring back there is pretty good shape actually.
 
johnnycuda said:
Yes, my oil and temp gauge work fine, it’s just the fuel gauge.
As far as testing continuity, I think it’s the purple wire do I pull that bulkhead off on the back of the gauge? I don’t wanna break it. The wiring back there is pretty good shape actually.
Click to expand...
If you're referring to the large round plug on the circuit board, yes, I'd pull that to do a continuity or resistance test. Just spray it good with penetrating oil first and gently pull it straight out....don't pull sideways to get it loose or you might loosen the circuit board pins. If you're careful where you pry, using two flat blade screw drivers (one on each side), works well. Just be careful you don't cut a copper trace on the board.
 
Questions what is IVR?
And why did my original test not work? That’s the way I’ve been testing it for years.
 
johnnycuda said:
And why did my original test not work? That’s the way I’ve been testing it for years
Click to expand...
Your first test, grounding the sender wire at the tank should have worked

IF ...

  1. The wiring from the sender to the cluster is good.
  2. The connector on the cluster cir board are good and making contact with the connectors on the wires
  3. The gauge is good

That the temp gauge works is a good sign
 
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