  We present results for non-adiabatic single-parameter pumping in a ballistic
graphene field-effect transistor. We investigate how scattering from an
ac-driven top gate results in dc charge current from source to drain in an
asymmetric setup caused either by geometry of the device or different doping of
leads. Charge current is computed using Floquet scattering matrix approach in
Landauer-B\"uttiker operator formalism. We single out two mechanisms
contributing to the pumped current: Fabry-P\'erot interference in open channels
and quasibound state resonant scattering through closed channels. We identify
two distinct parameter regimes based on the quasibound state scattering
mechanism: high and low doping of contacts compared to the frequency of the ac
drive. We show that the latter regime results in a stronger peak pump current.
We discuss how back gate potential and temperature dependence can be used to
change the direction of the pumped current, operating the device as a switch.
