Fuel pump or regulator?
 

I just bought a '95 A6 Quattro wagon. When cold, or after sitting for a while, the engine will turn over for 5-6 seconds before starting. When starting after only a short period being turned off, it starts immediately. Dealer said it needs a new fuel pump, at $685. It seems to me there's a slow leak and the pressure is gradually bleeding off. Could it be the regulator is faulty, or even just the regulator o'rings??? Thanks!