Fuel vapors?

what could cause this,at the pump my tank will shut off after 8gallons, i can force it to take more but then i get gas vapors in the cab,almost to the point of being undrivable,i've checked the vent lines,presure and return lines,they seem to be in good shape,theres no fuel leeking around the tank,that i can tell without pulling the tank. Any Guesses.(in case it matters its a 91 w/4.0

Any visible dents? Have you checked the inside of the vent line runing from the filler neck to the tank

chris

I have not done that yet. Will try...

Thanks