Sonex fuel level probe and MGL calibration

[bvolcko38]

Does anyone have experience on calibrating the Sonex fuel level probe with MGL efis?

[Onex107]

It's been several years since I did that. but there were no problems. I started with an empty tank, nose dragger, and added car gas in two gallon increments, recording the probe resistance at each level. I'm at 220 hours on the hobbs and I have considered doing it again. When I add a known amount of gas to a reading on the gage it doesn't add up exactly to the tenth. I don't fly below an hour in the tank so I'm not worried, just curious.

[Brett]

Just on a side topic do you run auto gas all the time? I thought the probes fall apart if auto fuel used? Ive stuck to avgas mainly as I love the accuracy of the level prob.

I had no isses with the calibration. Filled in 5 litre increments and wrote the numbers down so i dont lose them if my efis gets updated or reset.. has happened once already.

[wlarson861]

I run primarily auto gas and have had no problems with the probe. As I understand it, alcohol will destroy the probe. I run 91 octane unleaded fuel.

[Brett]

Oh ok... thanks for the clarification. I think I'll start testing auto fuel out then.

[Onex107]

Like Bill, I only run auto gas, ethanol free. He tells me that when he has to add 100 LL the probe does not read correctly. I haven't had to do that. Evidently the resistance is different for the two fuels.

[sonex892.]

Hi Brett
I use the princeton (sonex) sender with MGL. Mostly I run 98 octane unleaded, using avgas only when I have to. My experience is that alternating between fuels does not make any difference whatsoever to the fuel gauge readings.
Steve
Sonex 892

[bvolcko38]

Where did you find the instruction to record resistances at different fuel levels? It seems that I've read that somewhere, but now that I'm at that stage, I cannot find it.

BV

[Murray Parr]

Does anyone know what the empty calibration numbers should be? On my MGL IEFIS ( Discovery Lite) it shows 2760 and when I added 15 litres of fuel it still shows 2760 so I aborted the calibration in search of help instead. The RDAC pull up resistor is on as per instructions. I am scratching my head wondering why it isn't changing with more fuel (98 Octane unleaded Methanol free) being added.

[wlarson861]

make sure the probe is grounded, my ground disconnected and it stopped working