We present measurements of the magnetoresistivity of a weakly interacting 2D electron liquid in an unexplored region near the boundary of the 2D electron gas supported by a liquid helium surface. The magnetoresistivity is calculated by Dykman in the self-consistent Born approximation. For fields greater than a field B0, the magnetoresistivity is proportional to (muB)^3/2, where mu is the mobility. Electron-electron interactions cause a crossover to the Drude behavior as the density is increased. All of our data scale with the density-dependent parameter B0 as B/B0, with the magnitude of the magnetoresistivity scaled as 1/n. For low electron densities and fields less that B0, the resistivity is “Drude-like”. This regime is not understood, but again the same scaling can be applied.