[Diy_efi] Sending unit confusion

[Robert W Hughes]

TRy connecting the case/mounting flange to ground.

> in my never ending quest to conquer this circuit, i have encountered 
> something very strange. when i removed the fuel level sending unit to try 
> and test my circuit, i found that i am not able to simulate its electrical 
> function.
> the sending unit has 2 wires, a yellow and a brown w/ black tracer. when the 
> sending unit is not plugged into the body harness, the yellow wire has 
> +12vDC (or whatever battery voltage may be) on the body harness side of the 
> connector, and the brown w/ black tracer has approximately 15k of resistance 
> to ground, or 35mV of positive voltage.
> 
> when the connectors are plugged in, the yellow wire will have anywhere from 
> 0 to 3.5vDC, dependent on the position of the "float". the variable resistor 
> will have resistance ranging from 0k to 55k.
> 
> now, my problem is, i can't simulate the variable voltage outside of the 
> vehicle, to test my circuit. if i put 12vDC into the yellow wire, the brown 
> w/ black tracer will also have 12vDC, so what could that wire possibly be 
> doing, or connected to, that would make the circuit and unit work properly?
> 

-- 
Robert W. Hughes (Bob)
BackYard Engineering
29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
Houston, Texas "The city with too much Oxygen"
rwhughe at oplink.net

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