Gauge Wizard (After-market fuel gauge fix - matches any gauge with any sender).

Discussion in 'Internal' started by Gingerbus, Apr 4, 2016.

  1. [​IMG]

    Fuel gauge problems plagued my bus for years. With the needle leaping around and randomly dropping off the scale I never really knew how much fuel I had except by filling and working out how much is used. Convinced that the sender was at fault I duly cut the inspection hole to fit a new one. While the sender isn't damped for sure and causes the gauge to leap around violently when less than a quarter full, that's normal. It tested out just the same as a replacement.
    So I tried a stabiliser on the gauge as it never had one - that wasn't the problem either.
    The gauge itself however had broken insulators causing the contacts to short out and eventually packed up altogether. I got another gauge but had second thoughts about dismantling the head unit as it might explode into a thousand million pieces.

    So I bought a marine multi-gauge since it had oil pressure, temp and volts as well as a fuel gauge all in one unit - perfect for the spare binnacle.


    Great! Except the fuel gauge (and pressure) use US standard resistance senders at 33-240ohms. Our fuel senders range 10-70ohms (or thereabouts) so I bodged things for a while by adding resistors but always wanted to get an accurate gauge. Then I found this:

    Basically it allows you to match any sender with any gauge.
    You calibrate the gauge first by pressing buttons to move the needle to min and max points - in this case full and empty - and then calibrate the sender to the gauge to show Full, 3/4, 1/2, 1/4 and Empty. This can be done with the sender or by using a variable resistor, which is what I did with a 100ohm potentiometer.
    It also allows you to mark a low level warning lamp to light, then flash, at two more points on the gauge.
    In addition there's a second connection for aux use such as a buzzer or relay, but I didn't need that.

    Also it has settings to damp any sudden variations in input signal.

    So, back to the sender and the resistance range. I'd noticed that as the lever type sender moves in an arc from horizontal to near vertical, the gauge normally drops through the first 3/4s of the gauge then slows down and actually reads 1/4 full at half a tank.
    I plotted an arc and then worked out
    resistance levels for F, 3/4, 1/2, 1/4 and E needed to get the gauge to move in a more linear fashion.
    Then used the variable resistor to achieve those values (to simulate sender movement) and entered these into the gadget.
    Then went for a drive to test it out seeing as I was around 1/4 full.
    Lights came on near empty. Got to a garage before I needed the Jerry can and filled up. It took 50 litres.

    Now my gauge reads correctly, and I get a warning light at around 12 litres left which starts flashing at around 10.

    It hasn't completely eradicated the sender float movement with fuel sloshing around the long thin tank when near empty but it dampens the needle movement quite well now.

    Great little gizmo. Can also use to match pressure gauges.
    Last edited: Apr 5, 2016
    nigelcp, Terrordales, chad and 4 others like this.
  2. Great idea! Have you got a link to the guage as it looks pretty nifty?
  3. Sure. They're on eBay if you search Gauge Wizard, or save £4 and go direct to Spiyda Design. I'll find the URL.
  4. They're half the cost of similar ones for sale in the USA.
  5. Sure. They're on eBay if you search Gauge Wizard, or save £4 and go direct to Spiyda Design. URL reposted above.
  6. Baysearcher

    Baysearcher [secret moderator]

    I have no idea what most of that means but well done anyway!
    mgbman and Gingerbus like this.
  7. fix for a fuel gauge problem
    Baysearcher likes this.
  8. Baysearcher

    Baysearcher [secret moderator]

    That's the bit I did get!
    3901mick and Gingerbus like this.
  9. nice write up, nifty little gadget.

    I suppose you could get this to work with a standard fuel gauge as well?
  10. Sure, although I'm not sure what you'd gain, depending on symptoms and causes. A bit of needle damping I guess. If if all 'works' but the needle deflection isn't right it should allow you to correct that. You'd need to know what your sender is doing in terms of resistance. Taking it out and measuring it, or alternatively running it from full to empty and measuring both resistance readings.
  11. I got to a similar point with working out complex parallel and series resistor circuitry to try to fix it before I found this thing!
  12. Nice tinkering!
    Gingerbus likes this.
  13. ron


    there,s a lot of electronic gauges on the market that be calibrated to the fuel sender , i checked my sender gallon for gallon ended up as a straight line graph
    Gingerbus likes this.
  14. In this case I didn't want any single gauges and chose a four function one to fit in the spare binnacle, and could only find one model, a US spec marine multi gauge, that fitted the bill, hence needing to frig around to match it.

    Sent from my iPhone using Tapatalk
  15. redoxide

    redoxide Guest

    that gizmo looks the biz and I imagine it would match the VW senderto the VW gauge fine ..:) might look at that route..
    Gingerbus likes this.

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