what type of gasket are you using at top of the tank for sender.
I noticed if I overfilled the tank or filled it then parked it in the sun and the gas expanded enough to fill the tank. The gasket would weep just enough to smell. One drop of gas goes a very long way for smell.
I noticed my vented gas cap to a lot of pressure to vent. Most likely your paper was venting more than the one with the better seal.
I solved my problems by splicing a T in the vent line behind the seat. Put a loop behind inside metal up and back down so it was above the gas cap then put a vapor canister under the truck bed.
No issues with pressure or venting smell of any kind since it all goes thru the vent.
