One problem related to auxillary tank selector device has been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Fuel was moving from 1 tank to the other, causing spillage. Recall was issued & taken care of by the original owner. Manufacturer would not acknowledge repairing the problem for the second time. Consumer purchased the kit pertaining to the recall & put part on & had a repair shop to do the rest.