Gremlin in fuel reading - any ideas?

Gremlin in fuel reading - any ideas?

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Moto

Original Poster:

1,230 posts

252 months

Thursday 17th April 2014
quotequote all
The fuel gauge on the Vixen has just started playing up. With ignition on it indicates just over empty however much fuel is in the tank. The gauge is working as the park (ignition off) reading is well below empty, so it does move up when the ignition is turned on.

I put a volt meter on the fuel gauge and it gave a continually fluctuating reading of between 3v & 9v. Is this right???

I have also found what I think is a voltage stabiliser behind the dash. 4 terminals with 3 green wires :



Can someone confirm this is what I'm looking at. All gauges are Smiths (not original AC) and others all seem to read correctly.

Final question is how can I test the gauge, stabiliser & sender to ascertain where the fault is. Or do I have to replace each until problem fixed confused

.... Thx

griff 200

509 posts

192 months

Thursday 17th April 2014
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I would check if with a 12 volt supply engine not running . With tank unit disconnected gauge should read fully one way short to a Good earth gauge will be opposite etc . I'm sure besides bad earths and faulty voltage regs senders are the most likely cause but testing with ohm meter after removal will soon test it. You never know the float may have fell off. Good luck richard.

RCK974X

2,521 posts

148 months

Thursday 17th April 2014
quotequote all
That unit is a classic 'hot wire' type voltage regulator, and so a typical multimeter will show voltage switching between 0 and 13 volts.

Shorting fuel sender to ground should show maximum fuel reading on gauge, and disconnecting it should show zero.

Sender should have a resistance between something like 350 and 15 ohms, and it wouldn't be such a surprise if the sender 'button' has come loose or fallen off.....seen that a couple of times.

Moto

Original Poster:

1,230 posts

252 months

Friday 25th April 2014
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Thx Guys. Followed your suggestions to prove VS, gauge & sender OK. Got to the source of the problem, a leaking float in the tank.