Series 638 – Section 2.4 High Pressure Fuel Lines

Section 2.4
High Pressure Fuel Lines

High pressure fuel lines deliver fuel under pressure of up to approximately 45,000 kPa (6526 lb/in. ² ) from the injection pump to the fuel injectors. The lines expand and contract from the high-pressure fuel pulses generated during the injection process. All high-pressure fuel lines are the same length and inside diameter. Correct high-pressure fuel line usage and installation is critical for proper engine operation.‪

Use extreme care 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.‪

Section 2.4.1
Repair or Replacement of High Pressure Fuel Line

To determine if repair is possible or replacement is necessary, perform the following procedure. See Figure "Flowchart for Repair or Replacement of High Pressure Lines" .‪

Figure 1. Flowchart for Repair or Replacement of High Pressure Lines

Section 2.4.2
Removal of High Pressure Fuel Lines

Remove the external high pressure fuel line as follows:‪

1. Remove high pressure fuel line retaining nuts from electronic fuel pump.

   NOTICE:
   Do not damage the bleed line nipple when disconnecting the fuel lines.‪

2. Disconnect high pressure fuel line from the fuel nozzle(s), as necessary.
3. Remove attaching hardware securing high pressure lines to cylinder block.

Section 2.4.2.1
Inspection of High Pressure Fuel Lines

Inspect the external high pressure fuel line as follows:‪

1. Inspect the external high pressure fuel line for stress cracks, flared ends, gouge marks, bends, or damaged retaining nuts.
   1. If any damage is found, replace as necessary. Refer to "2.4.3 Installation of High Pressure Fuel Lines" .
   2. If no damage is found, reuse the high pressure fuel lines. Refer to "2.4.3 Installation of High Pressure Fuel Lines" .

Section 2.4.3
Installation of High Pressure Fuel Lines

Install high pressure fuel lines as follows:‪

1. Connect the high pressure fuel lines to fuel nozzles.
2. Connect high pressure fuel lines with nuts to electronic fuel pump. Torque to 34-36 N · m (25-27 lb · ft).
3. Reattach high pressure fuel lines with attaching hardware and secure to cylinder block.
4. Run the engine to verify repair.