  Standard-model extension (SME) is an effective field theory introducing all
possible Lorentz-violating (LV) operators to the standard model (SM) and
general relativity (GR). In the pure-gravity sector of minimal SME (mSME), nine
coefficients describe dominant observable deviations from GR. We systematically
implemented twenty-seven tests from thirteen pulsar systems to tightly
constrain eight linear combinations of these coefficients with extensive Monte
Carlo simulations. It constitutes the first detailed and systematic test of the
pure-gravity sector of mSME with the state-of-the-art pulsar observations. No
deviation from GR was detected. The limits of LV coefficients are expressed in
the canonical Sun-centered celestial-equatorial frame for convenience of
further studies. They are all improved by significant factors of tens to
hundreds with existing ones. As a consequence, Einstein's equivalence principle
is verified substantially further by pulsar experiments in terms of local
Lorentz invariance in gravity.
