Well there's only one way for fuel to be coming out the vents.
Right?
The bowls are overfilling as the engine speeds up.
So what controls that?
Primarily its the float and needle and seat.
But when there's is too much pressure in the feed lines, the needle can get pushed off the seat.
Since this only happens when the engine speed increases, it would seem most likely that the pump is the root cause. We know this pump has an internal regulation spring that has too high a cutoff pressure. So it comes down to the external pressure regulator. It appears to be allowing the pressure to climb as the pump's output volumetric output increases.
Hopefully its something about the way this regulator is set and can be made to work. See what the instructions say. Try setting it down around 4.5-5 psi at idle. I can't be specific here. I bought a regulator but ended up never using it.
Feel free to check out the float system too. The fact that you can adjust it to different levels (at 900 rpm) just suggests that its not hanging up or has some other issue that keeps it from working.
