My 02 GMC 3500 Dump fuel gauge is broken. The gas gauge shows E and the fuel message board says low fuel. It has two gas tanks but no selector switch, and it seems to pull gas from both sending units at the same time, while keeping track of the total fuel amount. I tried installing a new sending unit in each tank, but that didn't solve the issue. Does anyone know how this system works--or know how to repair this problem
Thanks for any help you might be able to offer.