Fuel Pump question

[dickie14]

Afternoon all

I noticed a few more drips of oil than usual under the van recently, and poking around found a couple of things -

1. There was some mayo in the oil filler neck which smelt strongly of petrol
2. The hose that runs from the breather pipe on the fuel pump into the tinware was missing
3. There seemed to be evidence oil had been coming out of the breather pipe

I'm guessing this all points to a knackered diaphragm in the fuel pump (original mechanical type on my CU engine)?

Amateur question: Do I need to drain the oil before I take the fuel pump off for inspection?

Cheers,
Dickie