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New sending unit/ gas gauge issues

Cheapsunglasses

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Alright, I’ve got a fun electrical mystery going on. My 68 GTX has a tanks inc tank with the electric fuel pump. I was using a traditional swing style sending unit, but it never worked. So getting tired of not having a working gauge, I decided to get the “floatless” style sending unit. I also have an equus fuel gauge laying around just in case the factory one doesn’t work.

Before I installed the sending unit I looked it over, its stamped "10-73" like it's suppose to, it's the correct length. I also wanted to test it, so I laid it on the fender and temporarily wired up the fuel gauge next to the battery. Turn the sending unit upside down to make the ball go to the top, it read full, turn it over it read empty.

Fantastic, put it in the tank, which probably has 5 gallons. hook everything up and the factory gauge doesn’t work. So get the equus gauge back out, and it's reading over 3/4 of a tank, closer to 7/8. Thinking maybe a wire is backwards I flip the wires. I think that killed the gauge. So I break out the tester, start reading ohms and I have 18ohms at the sending unit, and all the way up to the sending unit wire at the dash. if im not mistaken 10 ohms is full, so it appears to be reading backwards

Any help is greatly appreciated, because I am completely lost.

Forgot to add the swing sending unit has a broken wire and the float ball is full off gas
 
Last edited:
explain floatkess gauge
Traditional float style with a swing arm for the float as we all know

This is a “floatless” sending unit, still has a float, but it’s kept in a tube, less likely to get hung up, used by Mercedes, and in airplanes if I’m not mistaken, and common in the aftermarket

E03B8B6D-D4C6-4D3A-9181-6F1BE0E9FFF9.jpeg


06C21F30-4ACE-4247-B0FE-2F1A37A0ADC7.jpeg
 
Sounds like the ohm scale was *** backwards... 73 full and 10 empty, believe it's GM's that work that way..
well unfortunately that’s not the case, but I talked to tanks inc and they’re working on sending me a new one

Kinda what I was afraid of, but I was just hoping it was something I did and not bad out of the box. Is what it is though, stuff happens :thumbsup:
 
well unfortunately that’s not the case, but I talked to tanks inc and they’re working on sending me a new one

Kinda what I was afraid of, but I was just hoping it was something I did and not bad out of the box. Is what it is though, stuff happens :thumbsup:
Unbelievable.. I've had nothing but good luck with those... I guess there are lemons waiting around every corner... Let us know how the replacement does...
 
Unbelievable.. I've had nothing but good luck with those... I guess there are lemons waiting around every corner... Let us know how the replacement does...
I must have gotten one from the Monday or Friday batch :lol:


I cut an access panel in, so it’s a bit irritating, but I at least don’t have to drop the tank anymore so it’s no big deal, mistakes happen
 
Unbelievable.. I've had nothing but good luck with those... I guess there are lemons waiting around every corner... Let us know how the replacement does...
When life gives you lemons.....you make lemonade. The device shown is a ""stilling well" to reduce turbulence of the measuring device contained for greater accuracy....commonly used in industry in a batch plant or process operation. Thought you might like to know....
BOB RENTON
 
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