  We have investigated the characteristics of the currents in a pump-driven
fermionic Mach-Zehnder interferometer. The system is implemented in a conductor
in the quantum Hall regime, with the two interferometer arms enclosing an
Aharonov-Bohm flux $\Phi$. Two quantum point contacts with transparency
modulated periodically in time drive the current and act as beam-splitters. The
current has a flux dependent part $I^{(\Phi)}$ as well as a flux independent
part $I^{(0)}$. Both current parts show oscillations as a function of frequency
on the two scales determined by the lengths of the interferometer arms. In the
non-adiabatic, high frequency regime $I^{(\Phi)}$ oscillates with a constant
amplitude while the amplitude of the oscillations of $I^{(0)}$ increases
linearly with frequency. The flux independent part $I^{(0)}$ is insensitive to
temperature while the flux dependent part $I^{(\Phi)}$ is exponentially
suppressed with increasing temperature. We also find that for low amplitude,
adiabatic pumping rectification effects are absent for semitransparent
beam-splitters. Inelastic dephasing is introduced by coupling one of the
interferometer arms to a voltage probe. For a long charge relaxation time of
the voltage probe, giving a constant probe potential, $I^{(\Phi)}$ and the part
of $I^{(0)}$ flowing in the arm connected to the probe are suppressed with
increased coupling to the probe. For a short relaxation time, with the
potential of the probe adjusting instantaneously to give zero time dependent
current at the probe, only $I^{(\Phi)}$ is suppressed by the coupling to the
probe.
