Pump failure was coincident with fouled plug/coil cyl #5. Codes were lean fuel mixture coil failure- basically the pump was replaced, I was out of town 4 hours from my home dealership, an 1 1/2 from the nearest Audi dealership. Lucky that a good honest foreign car specialist could diagnose the problem, as there is no specific code for this failure. It couldve been a fuel line clog / filter clog, or fuel pressure sensor.