fuel guage sender / EDM930

[alun]

hi guys,

i had an edm930 installed recently.  now i have a problem with the left tank reading.  it has been fine for about 2 months, now when i turn the engine on, i get a reading that is correct but it then drops away slowly over the next half an hour to zero.  next time i turn i fly it starts of correctly again, then the slow fall off to empty.  has anyone else ever had a guage that did this?   i am wandering if it is a fault on the sender or the edm (i suspect its the edm as why would it read correctly at the beginning and then drop??).

al.