Facelift, CF2 models: rocker switches in panel to one side of inset dash panel.
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fuel gauge not working - easy fix

Post by Gav » Subscribing Member » Wed Apr 05, 2017 1:37 pm
Joined: Mon Oct 31, 2016 7:52 am
Posts: 67
I thought I'd contribute rather than just ask all the questions....

So fuel gauge not working & the steps I took to cure it:...
Check 10volts present: if the temp gauge works, then there's 10v to both fuel & temp gauge. If not, check wiring from the voltage regulator behind the dash to the gauges. If ok, change out the voltage regulator for a modern 10v FET device, such as a Texas instruments UA7810CKCS or similar (Google '10v voltage regulator' or check eBay for it) Wire as per the manufacturers data sheet, although generally, with the heatsink of the device down, L-R you should wire it input (12v) common (earth) & output (10v) to gauges

If no output on (fuel) gauges: short the output side to earth. This should make the needle move. If not; duff gauge

Check sender unit wire loom connection: get beneath & clean the wire & contact going to the centre of the sender unit. In my case, it's a single 'bullet' connector. Clean this & re-crimp the female/wire connection if required. Next check the wire to sender unit by shorting the wire to ground. The needle on the gauge should top-out if the loom is intact

Check fuel tank earth: find a known good ground point & try earthing the tank to it. I did it by wedging a wire between tank/securing strap & wiring this to a known earth in the dash

In my case, it was purely a bad earth on the tank, which I have now sorted properly. I was lucky. I didn't have to drop the tank & remove the sender!...which is where my tale stops.

Re: fuel gauge not working - easy fix

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Post by Phil Bradshaw » Club admin » Wed Apr 05, 2017 2:04 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4494
Total current draw of the two gauges is about 400mA when cold so LM7810 will do (20p each or thereabouts)

TO-220 packaged LM7810 can be fitted inside an original regulator body for heat sinking (as in this Howto) -

  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

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