  We present new high-resolution infrared echelle spectra of V1647 Ori, the
young star that illuminates McNeil's nebula. From the start, V1647 Ori has been
an enigmatic source that has defied classification, in some ways resembling
eruptive stars of the FUor class and in other respects the EXor variables.
V1647 Ori underwent an outburst in 2003 before fading back to its pre-outburst
brightness in 2006. In 2008, it underwent a new outburst. In this paper we
present high-resolution K-band and M-band spectra from the W. M. Keck
Observatory that were acquired during the 2008 outburst. We compare the spectra
to spectra acquired during the previous outburst and quiescent phases. We find
that the luminosity and full width at half maximum power of Br-gamma increased
as the star has brightened and decreased when the star faded indicating that
these phases are driven by variations in the accretion rate. We also show that
the temperature of the CO emission has varied with the stellar accretion rate
confirming suggestions from modeling of the heating mechanisms of the inner
disk (e.g. Glassgold et al. 2004). Finally we find that the lowest energy
blue-shifted CO absorption lines originally reported in 2007 are no longer
detected. The absence of these lines confirms the short-lived nature of the
outflow launched at the start of the quiescent phase in 2006.
