competence fuel level

[astills]

I finally got my Princeton Fuel level hooked up today and had a problem with calibrating. I have a compentence level and have it set up right in the Dynon D10 EMS. I calibrated it the first time by draining all the fuel from the tanks (18.25 gals). I then went through the calibrating program, when I had 16 gals I added another 2.25 gals and hit full. It reutrned a full value of 17.2 gals.
I then empty'd the tanks again and went through the calibration again. When I showed 18 gals in the tank I added another .25 gals
and hit full. It again returned 17.2 gals. Is there a place in the latest software that I can change the full value, or is there someway to show a correct value of 18 gals.
Al Stills

 

[josok]

The Princeton probe has a setup of it's own, which has to be done first.
After that, the probe will only show what it sees, so fuel under and over the probe (filler tube) can not be measured.
Thirdly, since it is a capacitive probe, it will only be reliable with the same quality of fuel, in other words mogas and avgas will produce different values. Possibly even different brands will ruin the preciness.

Regards,

Jos Okhuijsen

 

[astills]

Jos,
Yes the competence level was calibrated before, I've had in plane for some time. Did not think of the amout of fuel in the filler tube
but its not 1 gals, maybe 1/2 gal at most. I have a Europa and the filler tube is a short run up the side of the plane.
Al Stills

 

[dynonsupport]

We see this sort of behavior in resistive probes all the time. If the last gallon or so isn't able to affect the sensor, then we simply can not measure it. In other words, if, towards the end of your calibration routine, you tell the EMS you've added fuel but the EMS does not see a sensor change, we aren't able to measure that last small bit of fuel.

In your case, you might try doing BOTH a fresh calibration on the probe itself and another calibration on the EMS (in that order).