GRT Avionics

Guys
I have 2 resistive float fuel gauges tied to the HXR analog inputs 3 and 4 these inputs calibrated fine 0-15 gallons.
on take off the gauges go to -34 and -44 respectively.
The gauges return to the proper quantity display after landing rollout.
any suggestions?
Thanks
Rob Henderson

This is odd.
What happens during run up?
How are the sensors grounded?
Are you using the HXr's internal pull up resistors, or do you have external ones?
Any difference, full or half full tanks?
In flight, what happens if you turn off the alternator?

Thanks for the response
During runup the gages read normal
Sensors are grounded at the forest of tabs on cockpit side of the firewall
Using the internal resistors
Fuel quantity does not make a difference
Have not tried to turn off alternator yet
I will recheck the grounds and fly without the alternator this weekend
-Rob

Okay. I was thinking that in flight the buss voltage might be a bit higher than low power taxi, but if you do not see this during runup that rules out that theory. When using the internal pull up resistors, you are measuring very low voltages - so any stray pick up might be important. The only signal I can think of in flight would be the transponder, but that should be intermittant. What else changes between run up and flying? I am stumped. I assume the HXr has a good ground to the forest of tabs?
I forget: if you look at the set up menu in flight, does it show the measured voltages? If so I would check them.

I flew today and it is repeatable as soon as the air speed begins to register the display reads -34 and -44, as soon as I slow down to where the airspeed no longer shows, the correct fuel quantity returns.
Looks like a display problem,
Tomorrow I will record a demo of a take off and landing
-Rob

Here is a demo recording of a fast taxi pass down the runway
-Rob

For the archives
Ben at tech support checked the demo and found I had programmed the fuel sensors into the HXr and the EIS.
I removed the settings in the EIS and the problem went away
Thanks Ben
-Rob Henderson