I'm at a loss here. New pump, new motor. Pressure at the pump shows 1200psi. At the nozzle, it's a super low spray. The only thing I'm left with is corrosion in the line somewhere? I've ordered new hose, not sure what else to do. Thanks in advance.
Try this, disconnect the High pressure hose from the pump next to the bay that's got the super low spray and connect the High pressure hose with the super low spray to that known good bay, start the bay that you connected the high pressure hose to and then go out to the bay and see if it's working correctly. If it's working correctly the problem is somewhere between the pump and the gun. You could have a check valve leaking by.
I had a problem like that a few years ago. New hoses & new CAT pump, but suddenly low pressure in Bay 1. We replaced the check valve & hose. Found strands of Teflon tape had created a blockage inside the new steel-braided hose. Took us longer to find it than fix it. Crazy!!