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  •  » Fuel Sender Ohm Question

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    7/15/2018 9:53 AM  #1

    Chaplin
    Senior 24-7 FYI Addict

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    Registered: 3/14/2015
    Posts: 1,027

    Fuel Sender Ohm Question

    The Speedhut fuel gauge comes with a bunch of pre-programmed Ohm settings that are designed to work with a variety of different factory sending units.  You can toggle through the various options and choose the one you need or you can custom program it.  I've got the 1970 22 gal tank which, I believe uses a 73/10 Ohm sending unit.

    Strangely, the Speedhut fuel gauge doesn't have a pre-programmed setting for 73/10 but it does have a 70/10 option.  I set it to the 70/10 option as it was the closest to what I needed and because I couldn't custom program the gauge (in order to custom program, it has to be in the car hooked up to the sender and my gauges are still on the bench).

    Once I get everything in the car I can custom program it, but I am curious what the impact will be of the 3 Ohm discrepancy on the empty reading?

    Or is 3 Ohms within the margin of error so that it really won't have any material impact on the gauge reading?

     

    7/15/2018 11:13 AM  #2

    wsinsle
    Senior 24-7 FYI Addict

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    From: Belle Vernon, PA
    Registered: 4/01/2013
    Posts: 1,711

    Re: Fuel Sender Ohm Question

    The easy answer is about 5% difference. I took 3/(73-10)*100 =4.75, but there are variables on how the resister affects the stock gauge or after market one for all that matters. Stock sending units are wound disproportional were after market units are proportional. Also you have to set the arm on the float with a set screw or by bending the arm. Your sending unit may be at 10 ohms at empty and 65 when full. Where as someone else's  may be 15 @ E and 72 @ F. Best answer is program it when you put it in.

    If this forum can't fix it, it isn't broke.
     

     

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