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Running out of fuel - gauge problem?


Jedi Hopeful
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Hi all,
Yesterday I managed to run out of fuel in my BT7 for the first time in 26 years ownership (fortunately only mile from home). The fuel gauge read nearly "1/4" tank at the time. I had replaced the sender unit a couple of years back, but at the time did nothing to the gauge.

How can I get the gauge to read more correctly and prevent the long walk home to get get my fuel can? Do I somehow need to calibrate the gauge?




Jedi Hopeful
Country flag
I had replaced the sender unit a couple of years back, but at the time did nothing to the gauge.


Did you put the sender in the correct direction?

Causal inspection makes one think that the float goes to the back, while in reality it should go towards the front. The previous owner of my 59 got this wrong, and carried a stick with him to check fuel levels after running out once.
I flipped the sender around and it now works perfectly.



Jedi Hopeful
Country flag
Hi all,
just took out the sender unit only to find the plastic float was half-full with petrol! The unit is only 2-3 years and has ruptured where gripped by the wire arm. Modern poor quality spares! I've put the old arm (55 years!) with a metal float back on a see how it gets on.


Jedi Warrior
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If the float fills up with fuel, it should ride lower in the tank and therefore the gauge should display LESS fuel than you actually have unless the float is sticking against the tank structure. But I understand the crappy design of the wire arm and plastic float. Fourteen years ago I replaced my original sending unit because I discovered that the wiper of the rheostat appeared to be worn almost in two. The first replacement unit had the wire arm and plastic float, and it filled up with fuel within a month or so of installation because of a crack at the very end of the wire. The replacement I received for it actually had a HOLE where the sharp end of the arm gripped the float. I sent that one back, and in return received one whose rheostat wire was wound so poorly that the gauge was so erratic as to be useless. The problem with the float is obvious: the end of the wire is sheared off in manufacture to leave a sharp edge that bites into the plastic. I would have thought by now that that problem would have been recognized and solved, but perhaps some of the bad ones are still out there.
A substitute for the plastic float is a brass float made by Ford that is identical to the plastic one in dimensions. The Ford part number is COAZ-9202-B.

I filed the end of the wire smooth because a sharp wire might also cause a crack in the brass. However, deciding that the replacement sending units were too poorly manufactured and unreliable, I reinstalled my original unit and it has been working fine now since 2002, in spite of the worn wiper.


  • Replacement float, COAZ-9202-B.jpg
    Replacement float, COAZ-9202-B.jpg
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Jedi Hopeful
Country flag
Thanks steve,
Yes your second sender is the same as my new one. Can't find the Ford float in the UK so ill see how the original one works out.
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