Fuel retaining and collecting structure for an internal combustion engine high-pressure injection system

The structure (25) has a number of sleeves (30) fitted about the conduits (12, 18) of a supply circuit (6) supplying fuel to the injectors (5) of an engine (2). Each sleeve (30) is tubular, and has a bellows type main body (30c), two opposite end portions (30a, 30b), and an outlet fitting (31) extending from one of the end portions (30a, 30b). The sleeves (30) are fitted to the conduits (12, 18) by fitting the end portions (30a, 30b) in fluidtight manner to fittings (19) at opposite ends (12a, 12b, 18a, 18b) of the conduits (12, 18). The outlet fitting (31) of each sleeve (30) is then connected to a catch header (33) by a respective connecting line (32), which connects the inner cavity of the main body (30c) to the catch header (33) to enable any fuel leakage from the conduits (12, 18) to flow into the catch header (33).