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Old 01-21-2000, 07:00 PM
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is there a way to make the gauge reflect more than what's in the tank?

I was thinking along the line of adding potentiometers or bumping up the voltage with batteries on the circuitry behind the gauge itself. I don't have the wiring schematics and am not an electrical guru, thus appreciate any help. There's a 56 ohm resistor behind the gauge but bypassing that resistor merely increases the fuel gauge only by a little.

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Old 01-21-2000, 07:23 PM
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Join Date: Jan 2000
Location: New Bedford, MA USA
Posts: 1,583
Why would you want to do this?. If you must, find a wiring diagram with resistance range on the tank sending unit. I believe these units work with very low resistances, generally less than 20 ohms full scale. The fuel gauge is basically a crude ohmmeter (well not too crude). To increase or decrease readings, either parallel or series resistors will need to be added to the circuit. Also, most of these sending units do not read in a linear fashion. Rather they usually produce a logarithmic resistance, that is as the tank is becoming empty, the resistance that the sending unit produces is higher or lower at one end of the scale and does not drop in a linear fashion as the tank becomes more empty. For example, if a full tank produces 10 ohms and an empty tank produces 0 to 1 ohm, a half a tank will not be 5 ohms. There are also damping capacitances in the circuit to prevent the gauge from bouncing around as the vehicle moves, corners, etc. Again an interesting technical exercise, but what are you looking to achieve??
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Old 01-22-2000, 04:09 AM
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tks jeff. reason being gas across the border (half an hour away) is half the price but the big boys have dictated that you're supposed to have at least a 3/4 tank to go over. and they check randomly!!

not too sure where the sender unit is, and if it is easily accessible to add the resistors in parallel (since i want it to reflect MORE than whats in the tank) any help there?

and was wondering if the mod can be done from the instrument cluster side. I've tried bypassing the 56 ohm resistor on the gauge but it wasn't very effective, gauge only moved up a bit. Figure the other components much be located somewhere else?

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Old 01-23-2000, 12:56 AM
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found the fuel tank sensor

wired a pot in parallel and solved my "problem". tks again jeff.
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