I can rev my engine to 4000 in neutral, and then in each gear with a flow and pressure guage. There's hardly any flow at all in neutral, but a considerable amount when in gear travelling. Besides, you mentioned you only have 38 psi, which is well short of the 41-47 psi needed....
EDIT: The only way to ACCURATELY test a pump is with a flow and pressure guage, not by acceleration..