Fuel Sender Ohm Convertor

[malazn mafia]

Hi, is there a device that can convert the output of a 0-250 ohm fuel sender to 0-1000 ohm range?

[russellw]

Hrmmm - it's more normal (and much easier) to step down. I'd be rather more inclined to add a resistor at the gauge end to step down the input. The Stewart Warner (the one I presume you have) style senders are typically 33-240 ohm (F to E respectively) whereas the Ford senders work in the opposite direction.

If your gauge is expecting 0-1000 (unlikely but anyway) then you need to reduce the gauge input by a calculated factor - assuming it is linear which most are.

You need to know the exact operating range (the gap between the empty and full actual reading) so that you can calculate the resistance required using this formula:

1/R1 + 1/R2 = 1/Rtotal

So, for example, if your 0-250 ohm sender is really a 33-240 SW style one then it has a 208 ohm operating range. You need to establish the same mathematical calc for your 0-1000 and then apply the formula above.

I'll work an example for you. Let's say (for arguments sake) that the 0-1000 is really 40-840 ohm then the range is 800 ohm.Thus you need the 208 ohm range to read across 800 ohm instead (actually the reverse really).

Thus 1/800 + 1/x = 1/208
Therefore x = 1/280

Thus you could use a 280 ohm resistor in the gauge winding to obtain a fairly accurate reading.

NOTE: This assumes a linear operation of the sender.

Cheers
Russ

[malazn mafia]

Thanks Russ. But I think this is in the realm of an electrical engineer. I'm no good with numbers and formulas. The Car I am working on is a BA falcon fitted out with FG running gear and electronics. The FG uses a fuel sender that reads from 0 to 1000 ohm, while ba is 0 to 250. How would I install a '280 ohm resistor in the gauge winding' of an FG?

I think I have a solution, I will attach the FG fuel sender potentiometer to the BA fuel sender floater, and work with that.

[Cashie]

Yep, use the fg sender.

[krawczuk]

goto ebay and look up fuel wizzard,....

[1968XTFairmont]

Hi All I'm new to this site and computers ,does anybody know the OHM resistance value for a 1968 XT Falcon/Fairmont fuel sender ? any information would be helpful Thanks .

[aussiblue]

These are handy https://www.jaycar.com.au/resistance-wheel/p/RR0700 and https://www.youtube.com/watch?v=n3joyToqpCc to test what resistance gives the correct readings at the dash. Test on a full and empty tank and once you have worked out what resistance gives the correct reading permanently replace it with a soldered in resistor of the value that worked correctly.

[Franco Cozzo]

Originally Posted by 1968XTFairmont

Hi All I'm new to this site and computers ,does anybody know the OHM resistance value for a 1968 XT Falcon/Fairmont fuel sender ? any information would be helpful Thanks .

VDO 2016 international catalogue mentions 73 - 10 ohms.

http://www.vdo.net.au/media/189570/2...-catalogue.pdf

Bottom of page 8/96 on the PDF, physical page number 6.

Not sure how accurate that is as the VDO catalogue is chock full of mistakes, but in my experience most stuff ex USA specs is 240 - 33 ohms but it seems this 73 - 10 sender does a lot of local cars.

Also while this thread is old as the hills to answer the OP's question, page 85/96 or physical page number 83 is the resistance conversion box thing that can do what he's asking for.

[aussiblue]

page 85/96 or physical page number 83 is the resistance conversion box thing that can do what he's asking for.

i.e.

Part No. Description 105.001 Ohms tester for resistance gauges 2-500 ohms105.002 Adjustment Pot

Is essentially a more upmarket version of the Resistance Wheel (but with some fine adjustment capability available) from Jaycar etc but with a lesser range and doubtless a much higher price.

[Franco Cozzo]

Originally Posted by aussiblue

i.e.



Is essentially a more upmarket version of the Resistance Wheel (but with some fine adjustment capability available) from Jaycar etc but with a lesser range and doubtless a much higher price.

?

Part number 410.063 is what I'm talking about.

[aussiblue]

Sorry I thought you meant this that is also on page 84 of that PDF catalogue.

https://www.ebay.com.au/itm/VDO-GAUG...-/323105667363

[1968XTFairmont]

Thanks for that information I will have a look at the PDF and go from there .

[aussiblue]

I just remembered I also have this that I haven't used for decades (well at least many years before I passed the EH Holden Panel Van that I inherited from my grandfather via my father) onto my nephew. It is in a Litchfield Tool Labelled Cardboard Box but Googling it today by the tag on the Box suggests https://i.ebayimg.com/images/g/ndQAA...ttA/s-l400.jpg it is an OTC tool sold by John Deere but perhaps like John Deere Litchfield also sold it. The plastic Case has a "Serviceguard" Label on the front and what looks like a thermal printed label "JT01633". Very similar to the VDO tester. It could also be used to work out what the value of and additional resister connected in series would need to be to make a gauge work correctly. I know it is going a bit off topic but I thought I would post as it might be helpful for anyone with similar issues to the original OP.

BTW I had to add an inline resistor to the temperature sender in my NB Fairlane as being a prototype with a unique prototye dash cluster and temp sender, I could not get a replacements sender that would work with the gauge so it was a matter of playing with a laser thermometer and my resistance wheel to get it all working; I could have perhaps also have similarly used the Serviceguard calibrator if I had thought of it.