Difficult To Fill

The fuel filler pipe check valve is stuck closed.
The Fill Limiter Vent Valve (FLVV) is stuck closed.
The Evaporative Emission (EVAP) canister drain hose is blocked or restricted.
The EVAP canister drain line check ball is stuck closed.
Any restricted vapor lines or hoses.
The EVAP canister is restricted.
A fuel with high Reid Vapor Pressure (RVP) characteristics.
A high fuel temperature.
The fuel filler hose/pipe is pinched, kinked, or blocked.