the best way to test the mechanical pump on my 330 with out removing from engine
Have a fire extinguisher handy, a bucket of water and big wet towel to be extra safe. Disconnect the fuel hose at the front of the fuel rail, the one that goes to the glass fuel bowl. Carefully/safely cap off the fuel rail with something creative. Briefly turn on the electric fuel pump to check for leaks at your temporary cap. Take the now loose hose coming from the glass bowl and stick into a deep clear container to catch the gas. A helper is nice at this point to hold your catch-container and to be safe. Turn on the electric pump then start the car. You are now running the car exclusively off the electric pump. Check for flow and volume coming from the loose hose, be careful about reving the engine because if your pump is good it will quickly produce quite a bit of gas. I'm sorry I don't have a spec, but you should get a quick strong flow right away and a cup or so volume within 10 seconds. Another tell tale of a weak pump might be to observe the small return line that dumps at the top of the tank filler neck, you should see strong piss flow at idle if your pump is producing. Disclaimer; I hope my memory is correct and I'm no expert, but I have done this test a couple of times trying to troubleshoot that pesky pump. My car is a GTC, not sure if it applies to other models.
