Dredging this one up again for an update.
In 2021 I had a loose water separator on the port motor that caused the motor to completely die. It would suck air and die off. I could almost predict when it would happen. 45 minutes of run time, then it would die, but could be started immediately. Found the water separator was loose. Tightened it up, and no problem.
Fast forward to this spring. I launched and could barely get the port motor to start. This is the same motor that I replaced the primary fuel pump in 2020 and had the loose water separator in 2021. So frustration is high at this point. We fiddled around a little and it started and was able to run at 1800rpm in the slip without problems. So the next day we took off up the Mississippi. About an hour into the trip we come up on the stern of a barge. The river is narrow so we have to wait for the right spot to pass. We had been motoring around at 1700 rpm and about 9 mph. I throttled up to pass and sure enough... the port motor dies off like it's fuel starved again.

I tried one more time about a mile up the river and it died again. Not wanting to get in front of a barge and have a problem we just sat behind it for the next 8 miles... at 4.5mph. Safety first! Kids not happy.
After many hours of staring at the fuel system and going over what I've changed and not changed I decided to research the little "lift" pump that takes fuel from the tank and pushes it to the main fuel pump on the front of the motor. That little pump is a Walbro FRB-20. Turns out that pump has a filter inside of it that needs to be cleaned! I took it apart last night and it was pretty much 100% clogged. So that pump was starving the primary pump which in turn caused the primary pump to fail. The bad news is the primary pump is now whining again so I'm sure I've damaged it in some way and shortened it's life.
Now I need to figure out how to clean the filter on the starboard motor. I don't fit in the front space in front of the motor so I need to find a small person that can help.
I'll leave some links here that might help someone in the future.
The primary pump I used in the original problem that started this thread.
https://marineenginedepot.com/fuel-pump-high-pressure-gm-pump-with-return?gclid=EAIaIQobChMI1az52rWi6gIVDNvACh0vLgIwEAQYAiABEgJ0TPD_BwEAn option that another user here found that needs a little modification to the harness to work. (move the plug to the other side of the pump) much much cheaper.
https://theropshop.com/shop/products/electric-fuel-pump-marine-power-438603-ra080023-556017The Walbro FRB-20 pump that is being used as a lift pump in advance of the primary pump.
https://walbrofuelpumps.com/frb-20.htmlThe wow moment when I cleaned the filter in the Walbro FRB-20

