Those two lines off the neck should be for venting, or at least one should be !! My boat has a built in tank with a vent hose running to the outside of the hull. Vent line exit should be higher than the tank and an upward loop before the vent. The idea is any water getting into the vent will not go into the fuel tank due to the upward loop. Learned this the hard way a few boats back. Motor kept stalling, water filter was full of water, cleaned/ replaced the filter and after a few hours it was full of water and a stalked engine again. Traced down the vent line and found water was pushed into the vent opening and directly into the fuel tank ( no upward loop) so...ended up cleaning entire fuel system, changed the vent outlet angle so water wouldn't be directed in, added the upward loop and never had a water in fuel issue again. Vented cap won't work in your situation, gotta create a vent line and at leadt one of those shown should be a vent. Disconnect and blow thru each one, you should be able to find where they go....let us know !!
