Gas tank pressure
 

We have a visible gas leak coming form the tank area that begins with the starting of the engine. Is the tank supposed to be under this pressure?

It seems like from what I've read that the tank itself should not be under this amount of pressure. We stated smelling gas two days ago, but oddly the truck was running better than it normally does. (normal: offensive gas mileage, no power, knocking, ticking) yesterday however was had a full gas breach from the tank.

I feel like the tank visually in good condition, no rust, and the cage is in tact, seems odd that it could have a leak in the tank itself and that this pressure issue may have had or is a contributing factor in whatever has failed.

Most likely it's from the output of the pump or the return line. Both of these are under pressure when the engine is running. Does your 4Runner have the access plate below the passenger seat? If it does, open that and check for leaks near the top of the pump. If you have a leak in a pressure line, you might be able to see the stream.