  Using instanton effects, we discuss the problem of fermion mass hierarchies
in an MSSM-like Type IIA orientifolded model with U(3)xSp(1)xU(1)xU(1) gauge
symmetry obtained from intersecting D6-branes. In the corresponding four-stack
quiver, the different scales of the generated superpotential couplings offer a
partial solution to fermion mass hierarchies. Using the known data with
neutrino masses m_{v_{\tau}}\lesssim 2 eV, we give the magnitudes of the
relevant scales.
