[RidgeRunner]

Darn, I posted then deleted. Shrek caught me. LOL!! I know a few COONARSE MAN, I call them friends, nice folks. Don't want a herd of them coming after me, dats for sure. Hard to understand what they are saying at times, no ear for the dialect. But I like to hear them talk.
I figure MJ and Aussie both would be scratching their heads to hear one speak. Decided to delete so as not to stir the pot. OOOps!

The fuel issue. I am trying to wrap my mind around why there would be a vacuum. I can understand a big air pocket in the unvented front of the tank causing issues with getting the tank 100% full of fuel. The big air pocket up front should not have any effect on fuel being sucked out the bottom thru a pick-up tube. As the motor sucks the fuel level lower and lower in the tank, the vent line should still allow air to come in and displace the outgoing fuel. If you wanted to test your theory try with only half a tank of fuel and see what it does. I wasn't gonna post anything "Helpful" because I am not sure of what I just wrote. BUT if the vent line is wet when the tank is full and you have a big air pocket up front, be mindful of fuel expansion. On a hot day that could lead to purging fuel out the vent. Nice boat too. If you find a way to make the stern higher in the water (besides strapping 55 gallon barrels to the side) let me know. I have the desire to pursue that one.