F900ex fuel qty erratic


Resolution:  Hi shield at outer probe has a tiny amount of conductivity to the Hi-Z wire.



The exact point where the shield ended, there is a brown ring, that was…..   possibly abbraded?




F900B EX QTY wire diagram


At power up, RH 500 hi


After 10 min, boost pumps on, all equal?????




Rh gnd-sh dead short

Rh glm

Rh glf low at 1000

Rh shm 500 wiggles!, left side side good.

Rh hlf 1000

Low gnd half scale

Lh: gnd-low 700m

Lh gnd hi 3000M

SL 700

Sh 3000

Sh 3000M. Good.

Turns out, the Shield to Hi on the right wing would vry from 300M to 1G Ohm.  RH OB probe shield termination was conducting a little.


results after repair: