2002 Sienna: Trouble getting gas into tank

Gas will not go into the tank without the pump cutting off. I am using the same stations I have used for years and have tried older stations as well. Same problem. Initially, about a gallon will go in sometimes more than the pump shuts off. I try again, a little more gas, pump shuts off. It takes me 1/2hr to get a half tank. I’ve tried filling the gas at a slower rate to avoid splashing the side nothing works.(also get spillage) Any ideas? Currently have 120K miles on van. I travel from Maryland to Boston quite frequently, so I need this fixed quickly. Someone mentioned the charcoal canister or a small tube that goes into the canister may be clogged. Any thoughts would be appreciated. Trying to be knowledgeable before taking to mechanic.

I am not the best person to try to explain this, but the is a frequently asked question.

Down the right hand side of the page buried under the Ask a Question and tons of other things is a little search box that tries desperately to hide itself from users.

If you type various kinds of key word combinations in there having to do with this kind of problem you’ll find lots of discussions of it.

Despite there being so many I don’t recall ever seeing anyone report a follow-up regarding their remedy (there can be more than one cause) - otherwise I could probably say something useful.

You have a problem with your ORVR (Onboard Refueling Vapor Recovery) system.

Here is an approach to diagnosis and repair suggested on a Hyundai forum ➔ Hyundai Forum — Slow Fuel-Fill Problem Diagnosis.
You may be able to find a similar discussion on the internet for your make and model.

I hesitate to say this, but pulling back the rubber collar on the gas pump so as to leave an air space between the rubber collar and the car's filler tube usually solves the problem. But you will be venting gasoline-laden fumes into the atmosphere.