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Anon
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Fuel gauge - how does it work?

Hi. My fuel gauge has not worked for ages, and as I had the tank off last week I had a look at it. I checked the float in the tank is moving, so it's not that, and I shorted the wire past the tank straight to earth, but no difference to the gauge reading. A electrical guy at work said it culd be an old type meter where it needs a resistance in the tank to heat up a spring on the gauge. Anyone know if that's right? My gauge moves off the bottom setting to 'empty' on power up, but goes no further.

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Mon 11 Jul 2016 @ 14:21 Edit this messageQuote this messagePMQuote this message
Anon
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fuel gauge

Have you checked that the tank is earthed ? The gauge works on resistance to earth.

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Mon 11 Jul 2016 @ 15:35 Edit this messageQuote this messagePMQuote this message
Anon
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Fuel gauge.

Hi,

As Jim has said if you take the wire off of the tank unit and earth to a clean part of the van chassis the fuel gauge will read full, if that is what happens the gauge is ok.
In which case the tank unit will be at fault.

doujoy

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Mon 11 Jul 2016 @ 16:54 Edit this messageQuote this messagePMQuote this message
Anon
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Yes, I checked that and no difference, indicating the gauge must be at fault...?

Do you know what type of gauge it uses, is it the sort that requires a large resistance to dissipate the electricity in the tak to make a reading, or a straight earth connection bypassing the tank will cause the needle to shoot up instantly?

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Tue 12 Jul 2016 @ 12:06 Edit this messageQuote this messagePMQuote this message
Anon
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Fuel gauge.

Hi Middld,

They are a slow read gauge because they are fed seven volts not the full twelve
because the voltage goes through a ballast resistor so the instrument panel only gets seven volts.

doujoy

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Tue 12 Jul 2016 @ 21:25 Edit this messageQuote this messagePMQuote this message
Anon
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OK, that makes sense. So i measured and i'm getting ~2.5 volts coming down the wire to the tank level sensor. Sound too low? I'd have thought i'd be gettign the full 7 volts down that wire.

Is the dial easy to get out of the dash?

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Wed 13 Jul 2016 @ 10:00 Edit this messageQuote this messagePMQuote this message
Anon
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gauge voltage.

Hi Middld,

The tank unit should have the same voltage as the gauges in the dash board 7 volts.

doujoy

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Wed 13 Jul 2016 @ 15:15 Edit this messageQuote this messagePMQuote this message
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