The 1/2 inserting the pump nozzle trick can work until the gas nozzle comes out when pumping gas which will probably result in a fire or getting yourself covered in gasoline. Most likely you have a dirty air filter on your gas vapor charcoal canister located either by the tank or under the hood. If there is no place for the fumes to go when pumping gas the pump will turn off. I say this because I had the same problem on my 2004 Suburban, when I found the filter it was clogged with road debris. Now that I cleaned it I can pump without false turn offs.

This is where the breathing tube ( venting pipe/valve system) is blocked or inadequate for the fuel flow.

Often just pulling pump nozzle a little way out will allow gas pressure from fuel going in to escape thus enabling easy fill.

You need a new inexpensive *fuel filler vent tube which is one piece. This will allow all the air in an empty tank to escape without constantly tripping the fuel nozzle.

I tried filling with the nozzle in all kinds of positions/ways and nothing... I'll have to check out those other options

Either a clogged vent tube or a problem with the EVAP system. Read this post on EVAP

http://ricksfreeautorepairadvice.com/eva...

I have a 2004 STi. Everytime I take the car to the gas station to fill up, it only takes about a gallon or two before it "stops" filling. Each time you start to fill it it only keeps taking a gallon or two sometimes less. What could possibly be causing this ? Any help and tips greatly appreciated !