When I go to pump gas the nozzle will keep shutting off as if the tank is full even though I only have a fourth of a tank of gas. Would it be the fuel filler neck. I just don’t want to change it if thats not the problem. The mechanic has already cleaned it incase it was clogged but that didn’t help.
Your mechanic will have to go into the ( year and model specific) repair manual for this problem. Each make can be different in different models, and in different years.
Some generalities are: modern cars vent fumes to the charcoal canister. If the vent doesn’t vent, and the gas nozzle doesn’t pull the fumes out during refueling, there’s a problem. This is where the repair manual, with its detailed instructions, can save you a lot of wild guessing.
There can be several problems. Sometimes a hose in the vapor recovery system may get kinked or another part fail, but often it is the driver’s fault. Are you, or another driver in the habit of topping off the tank when you fill up? If so that can damage the system and usually you will need a new charcoal canister. Your owner’s manual and likely a sticker on the filler cover will warn you about this. That repair is usually the most expensive. There are other possibilities so I suggest you have a mechanic check it out to determine what the problem really is before replacing anything.
i am NOT accusing , or inferring anything here, but…
prior to this starting, when you fill the tank did you usually try to get that “last little bit” into the tank? you know, after the nozzle clicked off you would try to get a little more in the tank? once the nozzle clicks, STOP filling your tank. some cars have a reputation for stopping the flow really often. it is usually developing a “knack” to know how to hold, position the nozzle in the fill opening. BUT, once the charcoal cannister is plugged there is no help but to replace it.
if so, you may have over filled the tank, and clogged the charcoal cannister on the overflow system.