resistive fuel sender

[beto]

I have setup the 10bit A/D Converter With this resistor-divider (see bmp) to read fro 0v (sender in R) to ~1.75v (max R sender)
and I use a PIc18f452 to read the resulting voltage, and send it to hyperterm
This work but no very well, manually moving the sender the readings is'nt stable there is variation, someties without move the sender!
another issue, a simple math operation I=v/r show the i aplied to my sender
i=3/510= 5mA this is safe current to prevent rupture of the sender...?