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TR2/3/3A gas gauge TR3


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Hi all does anyone have an educated guess about which component would go out first, either the gas gauge or the sender on a TR3. I am thinking it is the sender. The gauge shows a ¼ tank but is actually empty. In addition, has anyone tried to fix one of those gauges? I copied this essay about calibrating and repairing one from an MGA awhile back, but the task looked to difficult.

Mickey Richaud

Staff member
Country flag
Grounding issues are the first suspects, followed by the sending unit and the gauge.

At least, that's been my somewhat limited experience...



Great Pumpkin - R.I.P
Mickey Richaud said:
Grounding issues are the first suspects, followed by the sending unit and the gauge.
:iagree:In fact, I advocate adding a ground wire to both gauge and sender.
Reading high on a TR3 could also be a bad connection anywhere between the gauge & sender.

A quick test (if your rear cockpit panel is loose) is to short the sender connection to ground, and see if that makes the gauge read empty (or slightly below). If it does, the problem is the sender or it's ground. If not, the problem is the gauge or the wires to it.

The sending units do wear out over a very long time, and start reading high. But I was able to tweak the adjustments on the gauge so that 'E' was still slightly above empty; which was good enough for me even though it made the gauge very non-linear (read about 3/4 for a half tank of fuel).


Jedi Knight
Country flag

I would recommend you follow Mickey and Randall's advice to help isolate the problem. A good path to ground often corrects electrical problems in LBCs. If the gauge's accuracy is the problem, the article you have and Frank referenced includes how to adjust it. It is not really necessary to disassemble the gauge or build the tester to make some adjustments to the readings of a working gauge. Remove the gauge from the dash and loosen the two nuts over the diagonal slots in the rear of the case. Do not remove them, just loosen a 1/4 to 1/2 turn so you can slide the coils back and forth. Using some extra wire connect the gauge to the car, you will need to add a ground wire from the case to a suitable ground in the car. If you know how much gas is in the tank you can slide the nuts (and thus the coils) as necessary to get a reasonable reading. As Randall said, this gauge is not always linear so if reads well on the upper half of the scale it may be a bit off on the lower half of the scale. Maybe the trip odometer is back up for an inaccurate fuel gauge.


Country flag
Thanks all for your much appreciated input. I will do as you suggested. I would have responded sooner but we have had cut backs at work and I use the computer there.


Jedi Hopeful
My TR3 fuel gauge shows empty all the time.
When I turn the key the gauge goes from slightly below zero, to zero.
Checked my ground at tank and it's OK.
If I take a wire and raise and lower the float maually the gauge dosen't move.


Jedi Hopeful
Mickey Richaud said:
Grounding issues are the first suspects, followed by the sending unit and the gauge.
At least, that's been my somewhat limited experience...
I read what Mickey said then went down another path....getting late I guess.
After checking OHM's, wires for damage....
I finally checked the ground to the gauge and that was it!
Cleaned up the ground and the gauge shows 1/4 full.
Thanks Mickey.
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