Incident Overview
A pilot reported that after takeoff, the aircraft climbed normally to about 8,500 feet. During the climb, the pilot observed higher than normal exhaust gas temperature (EGT) and fuel pressure, along with lower than normal fuel flow. After leveling off and reducing throttle, the engine began to sputter. The pilot noted a slight loss of engine RPM while fuel pressure and flow readings remained unchanged.
Decision to Return
The pilot decided to return to South Lake Tahoe Airport. While en route, the aircraft experienced an additional loss of engine power. The pilot subsequently performed a ditching in Lake Tahoe. The pilot and passenger exited the aircraft through a side window and swam to shore.
Post-Incident Examination
The aircraft was retrieved from the lake. An inspection of the engine revealed that after minor repairs, it operated normally using the aircraft's own fuel system. The fuel boost pump could not be tested due to impact damage. The magnetos tested satisfactorily. The spark plugs were too rusty to evaluate, so other spark plugs were used for the engine run.
Investigation Outcome
No probable cause was determined in this incident.