Fuel leaking from a fractured fuel manifold feeder line that ignited on contact with the engine’s hot compressor rear frame, which resulted in an engine undercowl fire. The fuel manifold feeder line failed due to high amplitude fatigue because the fuel manifold resonance frequencies were within the engine operation range. Contributing to the incident was that the engine was overhauled about the same time as the most current fuel manifold configuration that addressed the high amplitude fatigue failure mode was introduced, thus it was not installed on the engine.