I am a new one to this but I have a 1986 560sl with starting problems. I had this completely tuned up by a good mechanic that changed plugs, wires, cap, rotor, all filters, etc as well as put a hi quality injector cleaner in the fuel tank. The original problem was rough ide, lacked power, but now it runs better with more power than ever. Now the problem is it just will not start cold, crank and crank or shoot some either and it will start and when warmed up runs great, restarts and is perfect except the idle is now down to 500 rpm which I belive too low. Someone told me the problem may be one fuel pump down. I did replace one of the pumps a year ago because it was leaking but not the other. I guess I do not know the purpose of 2 fuel pumps unless one is to help cold start. I would sure appreciate some advise as to what direction to look as my mechanic is stimped.