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TR2/3/3A TR3 Fuel Gauge or maybe it's a 4A ?????

karls59tr

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Here's the story: I bought a new sending unit from BPNW as I was having issues with the gauge needle swinging all the way to full even if the tank was not full. I installed the the sender and I believe I connected the wiring correctly. I added a ground wire at the gauge from the hold down bracket to a dash wing nut. When the ignition key is turned on ,but the car is not running the gauge needle goes to half way. When the car is running the needle tends to move to full. The thing is I do not see any B or T markings on the gauge terminals to be sure I have the green wire and Gr/BLK wires connected properly?? I believe I have the sending unit installed and wired properly. I did own a 4A parts car for awhile and I suppose I may have at some point swapped that gauge in the 3 not knowing at the time that they function differently. Can anyone take a look at the photos and let me know if this
IMG_20260508_094539.jpg
IMG_20260508_094554.jpg
is a 3 or 4A gauge and how to determine which are the correct terminals to connect the green (ignition switch) and Gr/BK to ground?
 
That sure looks the same as the one in my 4. The glass should be curved on a 3 and flat on a 4, but then I suppose the glass could have been swapped over. I also seem to recall the needle being longer and thinner on a 3, but It’s been a long time.

As far as the leads go, I remember when converting these cars from positive to negative ground, the only change (other than at the battery) was to swap the wires on the fuel gauge. Just swap the wires until the gauge reads full when it’s truly full, and you’re good to go.
 
Yep...later TR4 gage. I didn't catch..are you installing in a TR3?
Yes I installed this TR4 gauge in my TR3 years ago and forgot that I had done so. Unfortunately I have now installed a new TR3 sending unit that I got from BPNW. I now remember reading that the two gauges function differently? Wasn't there something about putting a resistor inline on the green( power) wire to make it work?? Is there a workaround that I can do to make a TR4 gauge work with a TR3 sending unit? I hope.
 
Questions like that are where Randall used to excel...
The TR3 and TR4 fuel gauges work exactly opposite of each other. Plus one uses 12 v. And the other 10 .+ from the voltage stabilizer.
Good luck figuring a work around.
Charley
 
The TR3 and TR4 fuel gauges work exactly opposite of each other. Plus one uses 12 v. And the other 10 .+ from the voltage stabilizer.
Good luck figuring a work around.
Charley
Guess I have two options....switch to a TR4 sending unit and add a resistor or switch to a TR3 gauge if I can find one for a reasonable price. Karl
 
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