We present a coherent timing analysis of the 2003 outburst of the accreting millisecond pulsar XTE J1807 - 294 .
We find an upper limit for the spin frequency derivative of | \dot { \nu } | < 5 \times 10 ^ { -14 } Hz / s .
The sinusoidal fractional amplitudes of the pulsations are the highest observed among the accreting millisecond pulsars and can reach values of up to 27 \% ( 2.5-30 keV ) .
The pulse arrival time residuals of the fundamental follow a linear anti-correlation with the fractional amplitudes that suggests hot spot motion over the surface of the neutron star both in longitude and latitude .
An anti-correlation between residuals and X-ray flux suggests an influence of accretion rate on pulse phase , and casts doubts on the use of standard timing techniques to measure spin frequencies and torques on the neutron star .