1992 OMC 4.3 Cobra

While lakeside tied up to a neighbor yesterday, I knocked the fuel vent off the side of my boat. Fearing an unwelcome wave, I plugged it with a dry rag. Then used the boat about an hour.
After sitting for awhile, I started the boat, ran about a mile and it quit. Obviously a fuel problem (the motor cranked, wanted to start but was starving for fuel) I removed the fuel filter. It was only half full with gas. I removed the stuck rag from the fuel vent (it was soaked from picking up spray) and gave it 15 minutes before trying to start the motor. My neighbor towed me in.

Anybody believe that the wet rag stuck in the fuel vent (the gas tank was nearly full) would cause a vacuum lock?
What the correct method for replacing the fuel filter? Should I fill it with clean gas first before installation, so as to prime the system?

Thanks you !

there a loop or a u in the vent line to the tank.

If that u or loop is holding water or gas it will cause a vacuum in the tank.

Yes fill it with fuel and dribble a frew table spoons in the carb before starting.

If the problem presents itself again you may need to clean the whole fuel system, maybe a half hour to a hour worth of work.