Measuring ohms
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More Turbo
Joined: Sep 2011
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Measuring ohms
I have a 1955 ford f100 stock fuel sender. I am trying to find out what ohms are in my sender. How do I measure this? I also have to include I had to pull my wiring harness because of bad wiring.
thanks
jerry
thanks
jerry
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Joined: Aug 2018
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Yellow wire, on one probe and touch frame on other probe. lower float to bottom, raise float to top, that is your range of Ohms. It will be linear, meaning 1/2 tank should be right in the middle of the range from bottom to full.
Parts Nerd Extraordinaire
Joined: Sep 2010
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From: Western NY
Guys, the stock fuel system DOES NOT USE OHMS MEASUREMENTS. The stock sending unit uses the The King-Seeley methodology. These sending units supply a full 6V through the heater wire in the gauge in the form of a square wave with the duration of the "on" being the variable determining the gauge reading. The longer the duration, the more fuel in the tank. It is this full 6v of current which heats the bi-metallic strip in the stock gauge that causes the gauge to read via a small gear train (that may adjustable?). Most after market sending units are simply a variable resistor (ohm measurement style) which is then measured by the gauge. Therefore, the sending units signal doesn't heat the bimetallic strip in the gauge as much. Unfortunately, the calibration of the after-market sending units and the stock gauges don't match up very well due to the differences in the principle of the signal and are considered incompatible.
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