Fuel Gauge

[SteveA]

I have a fuel sender unit which goes from zero resistance when tank full to about 70 ohms when empty. The trouble is the gauge always shows full as soon as I power it up. I've checked the circuit and there doesn't appear to be anything wrong there - is there a way of checking the guage in isolation? - or any other ideas what might be wrong, it's made by VDO.


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[TonyBrooks]

A bad negative connection on the gauge can cause all sorts of odd readings - probabaly moving towards full.



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[robind]

connect a different negative connection from a known source that works, with a spare bit of wire and it should work.
Regards

Rob

<hr width=100% size=1><A target="_blank" HREF=http://www.rejuvanu.com>RejuVanu</A>

 

[Stemar]

This may be a red herring, but if everything else seems to be in order, it may be worth investigating.

I don't know about boat instruments, but at least some cars have fuel and temp guages that work on a lower voltage through a regulator so the guages' calibration doesn't change with battery voltage. Feed one of these 12v and it'll show full irrespective of the true level, but possibly not for very long...

Good luck

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[SteveA]

Thanks for the advice - it's the first time I've had a chance to try and sort this out in about 4 years (tanks always full otherwise). I've a feeling the 'dirty' earth might be the answer - I'll hopefully be able to have a look this week.

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