Can't pump gas into my tank!!!

Iam sitting at Hess pumping gas into my X and it all comes flyimg back at me. Ok so then I brought my X to the dealer to get a diagnostic and they told me it was the vent control valve and the evap canister. The price tag $600. So I said ok and drove off (I hate mt local Nissan Dealer). So Tomorrow Iam buying the parts and replacing the Vent control valve and the evap canister. It looks pretty straight forward remove the broken parts and replace them with the new ones. If any one has some words of wisdom that would be greatly appreciated.... This all happened in november. You ask what have i been doing since then? Great question. I've pumping gas into my tank very very slowly.....

I think the fuel system is pressurized and that is what concerns me a bit...