  We consider semi-local F-theory GUTs arising from a single E_8 point of local
enhancement, leading to simple GUT groups based on E_6, SO(10) and SU(5) with
SU(3), SU(4) and SU(5) spectral covers, respectively. Assuming the minimal Z_2
monodromy, we determine the homology classes and the associated spectra after
flux breaking for each case. Our analysis includes the GUT singlets which have
hitherto been ignored but which play a crucial role in phenomenology. Using
these results we construct an E_6 based model that demonstrates, for the first
time, that it is possible to construct a phenomenologically viable model which
leads to the MSSM at low energies. The exotics that result from flux breaking
all get a large mass when singlet fields acquire vacuum expectation values
driven by D- and F-flatness. Due to the underlying GUT symmetry and the U(1)s
descending from E_8, bare baryon- and lepton-number violating terms are
forbidden up to and including dimension 5. As a result nucleon decay is
naturally suppressed below present bounds. The mu-term is forbidden by the U(1)
but is generated at the SUSY breaking scale when a further singlet field
acquires a TeV scale vacuum expectation value, driven by the spontaneous
breaking of the electroweak symmetry. After including the effect of flux and
instanton corrections acceptable quark and charged lepton masses and mixing
angles can be obtained. Neutrinos get a mass from the see-saw mechanism through
their coupling to singlet neutrinos that acquire large Majorana mass as a
result of the monodromy.
