If you have to run your boat in reverse to prime the pump, AND it won’t work well when your moving forward – plain and simple – it’s a real bad setup. No matter what you do, it sounds like your setup will eventually be responsible for prematurely burning our your pumps.
Most good bait well setups have an intake that will force water into well at speed not needing the pump at all. Your setup seems to do the opposite. Namely, suck water out of the intake at speed cause your pump to work harder – not good
As far as you immediate problem, it sounds like your pump is burnt out. Try to flush the line with a hose in both directions to make sure there are no obstructions and then test the pump again.
"I would rather have a German division in front of me than a French one behind me."
--- General George S. Patton