If your vehicle is showing gas pump nozzle keeps clicking off constantly while refueling, here are the most likely causes and the parts you'll need to fix each one.
The vent valve opens to let air and fuel vapors escape the tank while you pump gas. If it gets stuck closed or clogged with dirt, pressure builds up in the filler neck and trips the gas pump nozzle's auto-shutoff.
Habitually 'topping off' the gas tank after the nozzle clicks off can force liquid fuel into the charcoal vapor canister. This saturates the charcoal, blocking the vent path and preventing the tank from breathing during refueling.
If the fuel tank was recently removed for a fuel pump replacement, the vent hoses running alongside the filler neck may have been pinched or kinked during reinstallation, choking off the air escape route.
The filler neck often contains an internal check valve or anti-siphon flap. If this flap breaks or gets stuck, it physically blocks fuel from flowing down into the tank, causing fuel to back up to the nozzle.
On certain vehicles, the tank vents through a leak detection pump assembly. If its internal filter gets clogged by dust, mud, or spider webs, the tank cannot vent properly.