DD15 Fuel System Checks

Check as follows:‪

1. Check fuel level and correct if necessary.
2. Use DDDL to check for stored or active codes and repair if necessary.
3. Using DDDL, monitor the rail pressure while cranking the engine.
4. During cranking rail pressure should be above 150 bar.
   1. If rail pressure is not above 150 bar, go to next step.
   2. If rail pressure is greater than 150 bar, check for other related engine concerns causing a no start condition (i.e. Camshaft Position Sensor failure)..
5. Use DDDL to monitor quantity control valve current while cranking engine.
   1. If the current measures less than 2800 mA, go to next step
   2. If the current measures greater than 2800 mA, check for a short to power between pin 1 of the quantity control valve and pin 1 of the 120–pin MCM connector.
6. Crank engine for 20 seconds and monitor “LPP Outlet” pressure. Refer to “Low Pressure Fuel System Pressures”.
   1. If the gauge does not reach 30 psi; go to next step.
   2. If the gauge is above 30 psi, but below 40 psi; go to step 8 .
   3. If the gauge is above 40 psi, replace filters.
7. Crank engine for 20 seconds and monitor “LPP Inlet” suction pressure. Refer to “Low Pressure Fuel System Pressures”.
   1. If the gauge does not reach -3 in. Hg; go to next step.
   2. If the gauge is less than or equal to -3 in. Hg; go to step 9 .
8. Check for external fuel leakage and repair if necessary. Refer to “16.4 External and Internal Low Pressure Fuel Leaks” , “Diagnosis External and Internal Low Pressure Fuel Leaks.”
9. Check flow from the pressure limiting valve (PLV). Refer to “Diagnosis Pressure Limiting Valve (PLV) Leakage (Flow Test).”
   1. If no flow is noted, go to next step.
   2. If flow is noted; replace the PLV.
10. Install fuel system tool J-48707 and J-48708. This allows the engine to be isolated from the chassis.
11. Fill the single container with clean fresh fuel and prime the fuel system using the hand primer.
12. Crank the engine for 20 seconds.
13. Does the engine start and run?
    1. If yes, check for loose connections, kinked fuel lines, or issues related to the fuel tank. Repair or replace as necessary.
    2. If no, go to next step.
14. Watch the fuel from the J-48708 tank to the inlet of the fuel filter module. Is fuel reaching the fuel filter module?
    1. If yes, go to step 16 .
    2. If no, go to the next step.
15. Check the following components
    1. Check for kinked LPP inlet and outlet lines between filter module and pump.
    2. Remove and inspect the low pressure pump for wear or broken oldham connection.
    3. Replace fuel filter module and retest system.
16. Watch the return fuel going to the tank.
17. Are there large amounts return fuel as soon as the engine cranks?
    1. If yes, check the three filter caps for proper torque and seating. If this is OK, go to step 17b .
    2. Remove prefilter, coalescer, and final filters. Check for damaged or missing seals at the bottom of the filters
18. If all steps have been followed and a starting difficulty condition still exists, replace high pressure pump (for customer demo the low and high pressure pump will be serviced as an assembly).