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Alberto, the yellow, both in electrical cables and pipe work, signifies fuel. Therefore on the left (Port) wall, the yellow cable is the solenoid connection from the throttle lever, which would also normally have a yellow band around the grip. On the right (Starboard) wall, the yellow is the main fuel feed pipe from the tank, behind and under the pilot's seat. The cable visible under the instrument panel on the Starboard side is a brownish yellow, being a main electrical trunking.