We have constructed timing solutions for 81 \gamma -ray pulsars covering more than five years of Fermi data . The sample includes 37 radio-quiet or radio-faint pulsars which can not be timed with other telescopes . These timing solutions and the corresponding pulse times of arrival are prerequisites for further study , e.g . phase-resolved spectroscopy or searches for mode switches . Many \gamma -ray pulsars are strongly affected by timing noise , and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model . We present an analysis of timing noise over the population using a new metric for characterizing its strength and spectral shape , namely its time-domain correlation . The dependence of the strength on \nu and \dot { \nu } is in good agreement with previous studies . We find that noise process power spectra S ( f ) for unrecycled pulsars are steep , with strong correlations over our entire data set and spectral indices S ( f ) \propto f ^ { - \alpha } of \alpha \sim 5–9 . One possible explanation for these results is the occurrence of unmodelled , episodic ‘ microglitches ’ . Finally , we show that our treatment of timing noise results in robust parameter estimation , and in particular we measure a precise timing position for each pulsar . We extensively validate our results with multi-wavelength astrometry , and using our updated position , we firmly identify the X-ray counterpart of PSR J1418 - 6058 .