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Offline pinto bismol

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fuel gauge???
« on: August 23, 2014, 02:19:40 PM »
My 76's fuel gauge has never worked. Always assumed it was a sending unit problem, probably a float. Well, drained the tank. took apart the old sending unit and the float was gone! Dropped the tank and found it in several pieces on the bottom. Cool! Replaced the float and put everything back together. Well....fuel gauge still does not work. Ohmed everything, and it looks like it should work until it gets up to the instrument cluster. Kind of at a standstill trying to figure out what direction to go. new gauges? where and how much?
thanks!
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Offline Pintopowers

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Re: fuel gauge???
« Reply #1 on: August 23, 2014, 04:02:40 PM »
With the key on did you ground the wire to the tank sender and see if the guage rises?

SR

Offline pinto bismol

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Re: fuel gauge???
« Reply #2 on: August 24, 2014, 08:03:02 AM »
tried that this morning and it did nothing...grr
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Offline russosborne

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Re: fuel gauge???
« Reply #3 on: August 24, 2014, 05:17:34 PM »
Is there anyway to test the gauge with it out of the car? I have one from my 74 that I have no idea of it's condition and won't be reusing(I'm going all aftermarket gauges), if I could verify it works you can have it P.B.
I just realised that yours may be different than mine, which is just a plain stock one in the same panel as the idiot lights. But if they are the same the offer still stands.

Russ
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Offline amc49

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Re: fuel gauge???
« Reply #4 on: August 25, 2014, 05:44:50 AM »
You have to know the OEM low/high resistances and buy a cheap old school volume control or potentiometer that has those values in the spread of the part. Then simply hookup and set potentiometer to low and high values and attach to gauge to make it move.

Offline pinto bismol

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Re: fuel gauge???
« Reply #5 on: August 25, 2014, 06:38:25 PM »
can I get that in English please!
LOL
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Offline russosborne

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Re: fuel gauge???
« Reply #6 on: August 25, 2014, 08:20:05 PM »
A potentiometer(used as a volume control on tv's, radios, etc, back in the analog days) is just a variable resistor that you change the resistance of by moving the shaft. What he is saying is to find the high ohm reading and the low ohm reading, (which I think is 0 and 70ish, but I could be wrong) get a pot that covers that range, connect it to the gauge, and move the shaft to see if the gauge needle movement follows as it should.

Of course I am an electronic tech, so what he said makes perfect sense to me.  ;D
I used to have a big box with all that old school stuff in it, but it went away many years and many moves ago.  :(

Simple, right?  ;D

Russ
In Glendale, Arizona

RIP Casey, Mallory, Abby, and Sadie. We miss you.

79 Pinto ESS fully caged fun car. In progress. 8inch 4.10 gears. 351C and a T5 waiting to go in.
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Offline 65ShelbyClone

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Re: fuel gauge???
« Reply #7 on: August 30, 2014, 12:22:49 PM »
It should be a 10-70Ω sender, so a 0-100Ω potentiometer would be suitable. It would also be possible to use a jumper wire, a 47, and a 100Ω resistor to see that it moves up to around the full, 1/2, and empty marks respectively.

As far as testing a gauge out of the car, I can't find a straight answer on whether they need 5V, 6V, or if 5 to 6V is suitable. Either way, really easy to make a power supply with an LM780_ regulator and 9v pigtail from the 'Shack.
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