When fueling nozel shut of at anything above a trikle.what would cause that?

TSB 04-06-04-003A Tech. bullentin list new parts for fuel filler neck and hose for this problem. Check at GM dealer for updated parts for your truck. They will need the VIN # to check for you.

It's the vent solenoid gm has problem with them, it's located to the right to the tank near the rear