dumping fuel and pump psi

[the sand flea]

I have been chasing out some ethanol related issues and have all but one gremlin left to triumph over.

2007 Yamaha f150 idles fine in the driveway but when I take it out for a shake down run I can come up on speed with no problem. When I come off of speed it will idle down and start to run rough, and flood itself to the point of cutting off. It will also start to dump fuel from the port at the lower cowling port. It continues to dump fuel during idle.
Chasing the other issues out I have replaced the VST pump, the needle valve and seat, all the fuel lines under the cover, the pressure regulator and most of my wallet.
I tested the mechanical pumps and get 12 psi at idle.
Ideas as to why I’m dumping this fuel and is the 12 psi too much?

[Nautical]

Re check your installation of the needle valve and seat and the float for smooth operation inside the vst.

[rodbolt17]

dude. its an EFI set up.
the ONLY way to dump fuel is you either have a leak in a line or the pump or the VST needle cannot seat correctly and is dumping fuel via the vst vent line.
all are simple to check no other tools than eyeballs required.

[99yam40]

Rod , what about the 12 PSI?
Should it be just 10?

[rodbolt17]

what met cal lab calibrated the users gauge?

[99yam40]

Yea, you are right.
who knows if his gauge is accurate.
He should check it against other gauges
But if it is reading good, should it not be regulated to 10 psi