DD15 High Amplifier/Needle Return Flow (Version 4 Fuel System) Troubleshooting

This condition will exist if there is leakage at the flat seat for the amplifier solenoid valve. At idle injector amplifiers are not turned on, thus little to no leakage should be noted out the return line.‪

Note: When measuring needle/amplifier return flow, both measurements must be completed at the same time, but in separate containers. If these instructions are not followed, incorrect return flow measurements will occur.

First the amplifier measurement must be setup, then the needle measurement must be setup. When this is done, begin the test.‪

Amplifier Measurement Setup

Setup as follows:‪

1. Drain fuel system.
2. Remove banjo bolt (2) attaching the amplifier return line to the line for the low pressure pump.
3. Remove the bracket attaching the amplifier return line to fuel filter module.
4. Using the short banjo bolt supplied in J-48708 , plug the opening in the line to the low pressure pump.
5. Install the banjo bolt line from J-48708 to the amplifier return line. Must use original banjo bolt and seal rings.
6. Attach the opposite end of the clear return line to the J-48708 container.

Needle Measurement Setup

Setup as follows:‪

1. Remove the needle line transfer line (1–shown removed) from the inlet of the high pressure pump to the tee junction at the fuel filter module.
2. Using two caps supplied in the J-48708 , cap the banjo bolt fitting at the inlet to the high pressure pump and the tee junction going to the fuel filter module.
3. Remove needle return line from the fuel filter module.
4. Use one cap from J-48708 and cap the fitting at the fuel filter module.
5. Connect needle return line at the module to the clear return line supplied in J-48708 .
6. Attach opposite end of the clear return line to the opposite J-48708 container.

Return Flow Test

Test as follows:‪

1. Prime the fuel system.
2. Start the engine.
3. The maximum allowable amplifier leakage rate at idle is .035 liters per hour (1.18 Ounce per hour).
   1. If the volume is within specifications the system passed, return system to original condition.
   2. If the volume is out of specification, go to next step.
4. Turn engine OFF and wait two minutes to service any components of the high pressure circuit.Note: System may contain residual high pressure when engine is turned off. Allow the residual pressure to bleed off for two minutes.
5. Disconnect #1 (or next one in sequence) injector high pressure line.
6. Install J-48708 rail plug on to the fuel rail and torque to 40 Nm (30 ft/lb).
   
7. Start the engine.
8. Measure the flow from the clear return line to J-48708 container.
9. The maximum allowable leakage rate at idle is .035 liters per hour (1.18 Ounce per hour).
   1. If the volume is now within specifications, go to next step.
   2. If the volume is out of specification, remove J-48708 rail plug and reconnect fuel line. Go to step 5 .
10. Remove the suspect injector.
    1. Inspect injector O-rings and replace if necessary. Go to step 1 .
    2. If injector O-rings look OK, replace injector.