bucking occurs after every gas fill up and then occassionally on and off after that on 2001 Nissan Sentra

Weekly the car bucks and always after fill up

Asked by for the 2001 Nissan Sentra
I wonder if the canister purge valve is sticking open and when you refuel the intake manifold is filling with fuel vapors. I just looked there are two service bulletins from Nissan about the evaporative system having problems.
1 more answer
I dont think the bucking is associated with the gas fill ups. Sounds like you have a secondary ignition problem that needs to be fixed. (cap,rotor,wires, fouled sparkplugs, etc.)