3208 – Fuel Injection Lines

Fuel from the fuel injection pumps goes to the fuel injection nozzles through the fuel injection lines.

When fuel injection lines are disconnected or removed, always put caps or plugs on the ends to keep dirt out of the lines. When fuel injection lines are installed, be sure all clamps and dampers are installed in their original location.

Each fuel injection line of an engine has a special design and must be installed in a certain location. When fuel injection lines are removed from an engine, put identification marks or tags on the fuel lines as they are removed, so they can be put in the correct location when they are installed.


6N0037 Nut (For use with 7000 series nozzle).

Engines with “Pencil-Type” fuel injection nozzles use fuel injection lines which have 6.35 mm (.250 in) outside diameters, 1.60 mm (.063 in) inside diameters, and use a 5M7418 Nut.

Engines with “7000 series” fuel injection nozzles use fuel injection lines which have 6.35 mm (.250 in) outside diameters, 1.83 mm (.072 in) inside diameters and use a 6N0037 Nut. The “7000 Series” fuel injection lines appear to be identical to the fuel injection lines of the “Pencil-Type” fuel injection nozzles. However, they are not interchangeable because of the difference in the inside diameter and can be identified by the notch in the nuts on the “7000 Series” fuel injection lines. The fuel injection lines for “Pencil-Type” fuel injection nozzles do not have notches on the nuts.

The nuts that hold a fuel injection line to a fuel injection nozzle and fuel injection pump must be tightened to the correct torque. If the nut is loose, fuel will leak from the connection. If the nut is tightened too tight, the inside diameter of the line will become smaller and cause a restriction to the flow of fuel in the line. Use a torque wrench and a 5P0144 Fuel Line Socket to tighten the fuel injection line nuts to 40 ± 7 N·m (30 ± 5 lb ft).

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