WTH?? as I have said before, I am no expert, but this is pretty abc... that is frustrating!! So you are maxed out psi, 2 guages, no overflow/flooding, reg is good, but adjustments make no difference. No return. depending if there were any blockage, I would think that would lower the psi... thinking out loud here.... I wonder if air is getting in.... causing this somehow. Pump sucking air & forcing it in the fuel lines???