Lycoming IO540K1B5 engine fuel pump—pump failed.
Engine decelerated during cruise. Aux fuel pump turned on, engine rpm increased, aircraft returned to base, on ground noted, fuel was spraying from engine driven pump case drain line. On shutdown found oil level two quarts higher. Engine driven pump found failed, with broken vanes and signs of excessive overheating, causing cracks of pump body. Shaft had signs of blueish metal indicating high heat and shaft seal had disintegrated allowing aux fuel pump fuel pressure to enter engine accessory case. Pump replaced, oil drained, flushed and oil replenished. Found debris in FCU filter, filter cleaned and reinstalled. Engine oil filter inspected as precaution found OK, no contaminants. Engine runs c/out all parameters normal. P/No: 201F5003. TSN: 502 hours