I think perhaps your "diaphragm" may be compromised and the "hole" to drain such into the oil is plugged, perhaps by sealant.
Can you smell fuel in the oil at all? If so a rebuild of the pump is in your future, luckily it is pretty easy to do. The removal and replacement is more work and depending on your accessibility it may be a PIA.
Another question since the pump is not supposed to leak anywhere but a poor fitting or into the oil. So if there is anything above it in the fuel system I would suspect that first.
Dave Neptune