Fuel not transferring between tanks on ProStar

[Pro Star Cummins]

Right side is just for storage on pro star.
We had problems also wouldn't transfer over.
Replace left side sending unit in tank . We ended
Up replacing right side first then pump, did the jumper thing ,pain in ass to get to
Pump . Decided to replace it . Still had problem until we replaced left side
Unit. It fixed our fuel gauge issue also . Drain fuel from tanks
And replace straps if bad.