Fuel System Fittings
DO NOT use fuel fittings (main body) made of brass, copper, zinc, zinc plated or galvanized steel where it would make direct contact with flowing diesel fuel. Diesel fuel flowing through these types of fittings allows those metals to leach into the fuel forming deposits on the injector tips which fouls them prematurely.
Fuel fitting nuts, compression sleeves, and fuel line connectors made of brass are acceptable because diesel fuel does not flow across their surfaces.
Do not use PTFE (Polytetrafluoroethylene) thread sealing tape. PTFE tape may allow strands into the fuel system that could plug up the tight clearance fuel injectors causing failures.