It shouldn't make any difference. The black should be ground I believe. FWIW
Paul in CT
I was thinking that if I got the wires backward the pump would run backward and in fact I reversed the wires while using the battery as a source and the pump "died".
Why the elec pump??
My 6 volt Carter vane type (+ ground) has the polarity marked for proper flow direction. Does your pump have a model no. on it?