common problems include; main & fuel pump relays, leaking fuel pump check valve or pressure regulator, but most common and easy to fix is carboned-up intake valves. run a cupple of tanks of chevron super and also add a bottle of techron to each tank. should start faster and run better!
My 535is doesn't start as quickly as I think it should - this opinion is based on the experience of two other 535's that start immediately upon turning the key (one is a friend's 535is; the other is a 535i I bought recently). I replaced the plugs and air filter this weekend - seemed to help some. From what I see, the wires look good. I haven't gotten into the cap and rotor yet. Any thoughts would be appreciated. Thanks - Jay J