Screw you on a new fuel water seperator or INSTALL one after the tank if the boat doesn't have one - I would see how it runs on a remote tank before switching back to main fuel cell - (don't ask me how I know this
Remove your fuel line AFTER the fuel pump and pump fresh gas out before reconnecting fuel line - sitting for four years you may be looking at a complete fuel line replacement job if ethanol was used in the gas --
If its fuel injected first gas goes from the bulb to a particulate filter, then to the mechanical fuel pump, then thru a fine micron filter, then into the high pressure pump BEFORE the injectors - its really not hard to pull the fuel rail and injectors you just need to make sure you use all new o-ring seals when re-installing - as I understand it the FI cartridges can only be cleaned with an ultrasonic bath
What I have learned is if the high pressure pump gets gummed up , you may be looking at $$$$$$ to repair -
Those who would give up constitutional freedoms to elected officials in exchange for a false sense of security, deserve neither freedom or security.