If the Accel PUmp check doesn't reveal a problem, it may be the PV gaskets.
The PV gasket should keep out the fuel from the vacuum chamber. Some after-market gaskets are not the best. According to my Holley books, the triangular opening washer is an after-market version of the Holley washer with internal tabs.
They say "Never use the triangular one as you should never use after-market carb parts."
Of the two other types, the regular "O-shaped" one is for PVs with a shoulder and the one with internal tabs is for PVs with no shoulder.
There should be a "step". Look at this pic:
If the gasket were removed, you'd see the step.
Here's two OEM PVs with proper gaskets. The PV without the step, needs the gasket with ears to keep it centered:
This is the kind NOT to use:
