High fuel pressure

You may have a fuel pressure sensor going bad, especially if its mounted in a way that it picks up engine vibration. Both the oil fuel pressure and oil pressure sending units seem to have shorter livers when subjected to engine heat and vibration. These should be remote mounted on the firewall to isolate them. Here is a link to the fuel pump diagram and theory of operation provided by Rainbow Aviation it indicates how the pressure is set by spring pressure. 

https://electricmotorglider.com/2018/09/21/fuel_pump_912/

Thank you for your input.  I just spoke to Steve, at Aircraft Specialty, and learned his father flew yesterday morning and experienced the same thing.  They thing this may be a result of seasonal fuel changes.  I will run this tank out and refill to see if things improve.  This plane has been flying flawlessly for over 250 hours.