
I believe what your asking is if the F-16 has a reserve fuel load. The answer is no.
The term "trapped fuel" comes from an error the jet will give when the aircraft has an incorrect fuel load, such as too much fuel forward or aft, and will not transfer, or if there is fuel in the external tanks and not transfering and the internal wing tanks are empty, this can cause a "trapped fuel" indication. The pilot will get this indication in two places, on the HUD and in the PFLD next to the right leg. He will also get this on the MFD when selected to the correct screen to review faults.