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The '03 was the last of the sought-after ALH motor (not the problematic PD). As peppy mentioned, it has a single mechanical fuel injection pump. The pump is expensive (about $1800 from VW, at cost). Many people believe that they cannot be rebuilt, which is BS. Any Bosch injection specialist can rebuild it. A good rebuild runs well under $1000, exchange. A good used pump runs $500-600. The pump is on the passenger side of the motor in plain view (once you remove the cosmetic engine cover). It is run by the timing belt, so usually they will recommend doing the belt when they change out the injection pump (IP). To do it right you replace the belt, rollers, tensioner, and water pump which is about $350 in parts. It is about a 4 hour job for the timing belt 'kit' and another 1-2 hours to R&R and time the IP.
VAG COM can tell you exactly what's up with the pump and what's going on with timing. The pump has several complex moving parts that can wear out. The pump may hold perfect timing but still have hard-part failures.
Has he ever run bio-diesel? Does he run a lubricating additive with ULSD? These pumps have been failing left and right lately due to the lower lubricating properties of the new fuels.
Let your friend know I'd be interested in the car as-is.
I have one now with 281K miles
