So here what I did next. I got a cheap pump from eBay but the bellows seal leaks and I tried soldering it but it's not holding and the pump leaks. I will keep it for parts, at least the drive washer is in good condition. Meanwhile I verified the orientation of the impeller on my old pump. Then I went on doing voltage measurements.
At the pump terminals, engine OFF, pump connected, 9.5V. That's 3V drop from the battery.
At the fuse same conditions, 9.5V, so the drop is not on the wires going to the back.
At the pump terminals, engine OFF, pump disconnected, 10.5V, so something else is sucking 2V and the pump accounts for only 1V drop.
At the pump terminals, engine ON, pump connected, 12.5V, confirming something else is sucking 1V now when the alternator is helping to 13.8V at the battery.
On that circuit I have the coil and the alternator and since the coil is a couple ohms I am assuming that this is the big consumer. Other than that the pressure is quite stable at 9 - 9.5 PSI with the old pump and the eBay pump.
I am thinking that the 9 PSI is dictated by the IP outlet check valve and since I cleaned it with compressed air I must have made it open sooner and I never get to the 11 PSI. Maybe I should leave it and just watch the gauge to clean the screen every few tanks, when I pulled it out the screen had some stuff in it already. I would like to put one of those glass filters with easy to clean elements before the pump but they caution against using it in fuel injection and I do not want to restrict my pump feed further.