Low-Pressure Lines Are:

• the fuel supply line from fuel tank to fuel filter housing.
• the fuel return line back to fuel tank.
• the fuel drain line from each fuel injector.
• the fuel supply line from fuel filter to fuel injection pump.
• the fuel injection pump return line.

High-Pressure Lines Are:

• the fuel line from fuel injection pump to fuel rail.
• the four fuel lines from fuel rail up to the fuel injectors

WARNING: High-pressure fuel lines deliver diesel fuel under extreme pressure from the injection pump to the fuel injectors. This may be as high as 180,000 kpa (26,107 psi) . Use extreme caution when inspecting for high-pressure fuel leaks. Inspect for high-pressure fuel leaks with a sheet of cardboard. High fuel injection pressure can cause personal injury if contact is made with the skin.