pēxa only occurs with the locative preposition rū. rū NP pēxa means away from a location, with a connotation that away from is far away from. So, rū jahāwekien means ‘from the shore’ and rū jahāwekien pēxa means ‘[far] away from the shore’.
rūjapēxa is rū NP pēxa without a specified location, and so just means ‘away’.
ñi liēn rūjapēxa;
I went away.