Still can’t add fuel

[Jeffd]

I’ve had my ‘00 Boxster S since October and have never been able to add fuel without it overflowing and shutting off the pump. I replaced the purge valve (under the intake manifold) first as I had a CEL for that. It cleared the CEL but had no effect on the fueling difficulties. I then threw parts at it and replaced the tank bleeder valve which did no good. The one it replaced seemed to work exactly the same when I blew through it and manipulated the lever that’s pressed by the fuel cap.

Anyway, I can fill it to 3/4 tank fine if I disconnect the fitting that connects to the orange side of the fuel fill valve. Once it gets to 3/4 with that hose disconnected it shuts the pump off but that’s how I’ve been operating. I just leave the fender liner off and I disconnect that hose to fill to 3/4. Apparently there’s another vent valve at the top of the tank and I assume that’s the only remaining suspect. Does anyone know how to properly test that prior to throwing more expensive parts at this problem?