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Posted for Sky2high@aol.com:

If you are using Vision Microsystems fuel quantity monitoring system, you are limited to a minimum probe length of about 14 inches.  The three wires at the probe are ground, +5 volts and a square wave frequency resulting from a resistance capacitance (amount of fuel) circuit.  I used an 8-9 inch vertical probe in my header tank that produced a frequency too high for the computer with less than 3 gallons in the tank.  Frequency counts are what you report to VM for fuel level calibration.

I constructed a bump in the cable using the available power to drive a CMOS frequency divider.  Thus, the halved frequency was compatible with the computer and provides me with a very accurate measure of remaining header tank fuel.

Scott Krueger
N92EX

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