My 80 series would develop amazing in-tank pressures on a hot day. 30 seconds after you removed the cap, it was still hissing and spraying liquid fuel droplets out around the filler neck. I don't think that modern evap systems are truly vented to the atmosphere, even after all the charcoal cannister action. I'm convinced also that FJ55 gas tanks crack/rupture on the top due to pressure cycling - even back then.
Colo Springs, CO