250HPDI pressure at 1515 PSI. Too high? Ethanol?

[89 Grady White Project]

One of my 2003 250HPDI motors decided not to start after sitting up for 3-4 months, but turned over fine so during trouble shooting I discovered my vapor separator fuel pressure regulator valve was stuck wide open and the plugs were fouled. I replaced the regulator valve and cleaned the plugs and then ran the motor yesterday, but I noticed the secondary and high pressures were right at the thresholds of the Yamaha diagnostics tool so they changed colors between red and blue (normal). The secondary pressure ran at 10-11 PSI (recommended 7 +/- 1.5) and high pressure 1510-1515 (recommended 1000 +/- 150). As an experiment, I applied vacuum to the regulator valve to force a pressure drop from 50 PSI down to 35 PSI (verified with mechanical dial gauge attached to separator) but it had no effect. I ran the RPMs up to 2000, but no changes in pressures and then up to 4500 RPMs with no changes. I lowered the idle down between 850-900 RPM, but still no changes. The software did not go in the red very often or stay there very long, so I am right at Yamaha's recommended thresholds. I don't see any mention of a high pressure pump regulator valve in the service manual or the parts diagram, but I suspect they may have one since there is only 1 fuel line filter and 2 return lines. Since going into the high pressure pump will compromise all the seals and the software says I'm at the threshold, I'll probably keep running the motors but check the pressure regularly.

I've had to start using ethanol mixed gas (10%) and added STABIL for storage over the winter, so I hope this isn't causing the high numbers and parts failures because my other motor now shows the regulator valve isn't working right. I'm trying to run the motors every 1-2 months. Is there a pressure regulator valve in the 2 high pressure pump bodies? Anyone else had this problem and keep using the engines?

[rodbolt17]

ok
lets get on the same page.
low pressure fuel system, thats the lift pumps all the way to the VST.
medium pressure system.
thats the VST pump,regulator and inline fuel filter.
high pressure, covers everything from the the high pressure pumps to the VST return.
yes the high pressure pump has a regulator,no its not field servicable.
50 PSI is the minimum on the medium pressure but 60 wont hurt anything.
the pump is actually capeable of over 100 PSI thats why there is a regulator.
playing with the medium pressure regulator wont affect the HP rail pressure.
I would monitor both the reference voltage and output voltages on the high pressure sensor as there is no good way to actually monitor it other than the sensor.
only place so far that services the HP pumps is Flagship marine in punta gorda FL.