Embodiments of the present invention provide a phase separation float assembly, a phase separation detection system, and a method for detecting phase separation. One embodiment comprises a first float subassembly comprising a first float adapted for vertical travel along a fuel level probe shaft and a magnet. This embodiment also comprises a second float subassembly comprising a second float adapted for vertical travel along the shaft. The first float has a first density and the second float has a second density greater than the first density. The second float subassembly further comprises at least one stop feature which engages the first float subassembly when the first float subassembly travels vertically a predetermined distance along the fuel level probe shaft. The first float density is selected such that the first float subassembly travels vertically along the shaft to engage the at least one stop feature in the presence of phase separation.