Look at the size of the tube going from the fill neck to the tank. Stovebolt trucks always had a problem taking gas at high fill rates, at least since the late 1950's when I started pumping gas! A restricted vent system that won't let the air purge out of the tank easily will also cause the gas to back up in the fill neck- - - -the gas can't get in any faster than the air can get out!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!