Thanks for your prompt replies and keep them coming..
Yes, return lines from the pump/separator back to duplex Andair valve to each tank.
The electric boost pump was off, the engine ran smooth the whole flight, not to rich.
I'm pretty sure I noticed the pressure rise when I switched from the left tank to the right tank. I continued flying for a while longer, and when I checked the pressure back on the left tank, it was still high.
Possible causes: Bad gauge tranducer, blockage in the return circuit, bad pump, Skyview electrical. I have a call into ECI to discuss with their experts.