This is the diagnostic method I would try:
1.- Turn the key to the on position (do not crank) and listen for the fuel pump. If unsure of what you hear, walk around the car to where the pump is located. (Mine is somewhere behind the passenger's side rear wheel).
2.- If you hear the Hummmm, chances are the pump and relay are good, look for a spark problem.
3.- If no Hummmm, take the fuel pump relay out, jump the terminals, and place the relay back on the socket. (for this you will have to do a search, since I do not know the terminals from the top of my head, relay is located somewhere behind the battery in my car))
4.-If pump now Hummms, you know the relay is the problem, if no Hummm, the pump has a problem
5.- Try that first, and then we go for the spark problem (if any)
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car