2000 ficht 115 with error code 37 - water in fuel?

Hello,
I just had my engine error code read and it is coming up with code 37, water in fuel. I understand this sounds pretty straight forward but i guess my experiences have shown me its never that easy? Here is my problem with this error. The boat seems to run flawlessly at speed, smooth acceleration, engine runs smooth, UNTIL it will cut out for a mili sec, then check engine light comes on, but it keeps running perfect, BUt at idle it will again idle smooth not rough, but check engine light will come on, then after about 1 minute engine shuts off, i assume thats part of the check engine code, SLOW, or evinrudes safety thing to kill the motor. Anyway thats my biggest issue with water in fuel code, i have had that in cars, and you know there's a problem with your fuel, rough idle, spitting and sputtering, all that fun stuff comes with bad fuel. SO i guess im hesitant to trust this as the easy answer? Does anyone have anything they can add or suggest. Obviously im gonna change fuel/water separator (which i did unscrew and dump out, only to get that same check engine error code asap) And ill drain the fuel tank and put new fuel in it (sucks i have 20 gallons to drain? Is there anyway i can cut fuel line, or unhook somewhere near motor and run line direct into a 5 gallon can of new gas before i drain fuel tank??? might be a good test? sorry for all the rambling, im just trying to cover all the bases so i can hopefully get the some feedback without too many follow up questions,,,,, cause i just want to go boating for the love of god !!!! hahahaha....

thank a lot guys

Yes you can run a known good tank of gas to check for issues. Are you sure when changing the filter ya didn't mess up the sensors inside the filter? If they get bent and manage to touch it will set off the alarm.

You can also install a 10 micron inline filter between the tank and the engine. My understanding is that the H2O molecule is too large to pass through a 10 micron filter. Not sure if this is true because I haven't researched it but I've had one on mine for over 2 years with no water issues at seperator canister.