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Fuel Tank Calibration RV 14A

Allan Stern

Well Known Member
I am having a problem with the calibration of my right fuel tank. I go into the Calibration page on the GX3 and have filled the tank with various quantities of fuel, saving the calibration points into the system and saving all the data.

When I exit/reboot the unit and go to the main page, the right fuel tank is reading 0 fuel. Go to calibration, says it is calibrated. The Left tank has no problems and was calibrated same way. The fuel sender is grounded to the fuel tank and we know the wire is good as it calibrates. But again does not register any fuel quantities. And in flight it occasionally will come on and register fuel quantity.

This has stumped Stein Avionics which built my panel. So I am seeing in anyone with another 14 has had any similar problems. Or might be able to offer me some ideas as to what to look at.

Thanks

RV 14A 140507 flying
2020 donation made
 
Could the float be sticking? If you notice an erroneous reading, try smacking the top of the tank right above where the float is.
 
Diagnostic journey . . .

Calibration OK means the page has values so careful what conclusion is drawn based on that fact. Recommend ploting the resistance of those "calibration" values on the good and bad tank to see for sure if the values are making sense. The offender could have a very very small change (slope) compared to the acceptable one. So small in fact, that the resistance is so high that the reading yields a voltage so low that the panel rounds it to zero. Consider that your panel is doing exactly what is asked of it.

Also, a couple of points reading the actual resistance at the sensor might be of some diagnostic value to confirm this hypothesis.
 
Last edited:
Calibration

1. Have attached separate ground wire to sender -no change

2. Originally thought float might be hanging up on rib. Changed both floats and shortened wire bend slightly.

3. resistance changes as fuel is added, voltages change. 1.7+\- to .303
 
I got burned doing one of my tanks. Somewhere during the process, you have to hit enter twice for the data to be saved. Can't say whether or not the calibration values were there, but I was able to quickly identify the error.
 
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