DD15 Troubleshooting – Section 16.4 External and Internal Low Pressure Fuel Leaks

Section 16.4
External and Internal Low Pressure Fuel Leaks

This condition will exist if there is an external or internal leak of the low pressure fuel system. Tool J-48710 is required for this testing.‪

Test as follows:‪

1. Remove the fuel feed and return lines from the fuel filter module.
2. Install J-48710 fuel pressure test kit onto the module.
   
3. Ensure the shutoff valve is in the OFF position.
4. Turn regulator counter-clockwise until it stops. The regulator is now set to zero pressure.
5. Turn the shutoff valve to the ON position.
6. Once the system pressure has reached 30 psi, turn the shutoff valve to the OFF position.
7. The system pressure should not drop over 10 minutes.

   Note: The fuel cooler and feed line for the amplifier circuit is located behind the fuel filter module. Ensure this area is not overlooked.

   Note: When removing J-4870, point the nozzle away from your body and into a container.

8. If the system pressure drops off over 10 minutes, use a soapy solution and spray all connectors, fittings, and braided hoses.
   1. If no leaks are found, go to next step.
   2. If leaks are found, repair as necessary.
9. Remove oil fill cap and listen for internal air leaks.
   1. If internal leaks are found, remove the rocker cover to locate which injector seal ring is leaking.
   2. If no internal leaks are located, go to next steps
10. Install cooling system pressure testing tool.
    1. If cooling system pressure increases, replace fuel cooler located behind fuel filter module.
    2. If cooling system pressure does not increase, no problem found.