MBE 4000 DDEC VI Troubleshooting – Section 6.5 Engine Will Only Start Using An External Priming Source

Section 6.5
Engine Will Only Start Using An External Priming Source

Hard starting with external priming source indicates a system that cannot generate the required pressure for the high pressure pump.‪

1. Using DDL7.X (latest version), check for stored or active codes and repair if necessary.
2. Check fuel level and correct if necessary.
3. Check for external fuel leakage and repair if necessary.
4. Check prefilter cap for proper torque and seating.
5. Start the engine using an external priming source (remove once the engine is running).

   ENGINE EXHAUST ‪
   To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

6. Install the priming port gauge J-48876 and note the pressure at 600 rpm and 1800 rpm.
7. If pressure is below 60 psi, turn engine OFF and watch the bleed down rate of the priming port gauge.
8. Does the pressure bleed down to zero within two seconds after engine OFF?
   1. If yes, remove the high pressure relief valve for the low pressure pump and check for debris. If debris is found, replace pressure relief valve and inspect prefilter for damage or clogged. If debris was not found, remove all three filters and inspect lower seals for leakage. Replace if necessary.
   2. If no, check flow from the pressure limiting valve (PLV). If no flow noted, go to next step 9 . If flow is noted; replace the PLV.
9. Check for internal or external fuel leaks.
10. If the engine fails to start, call the Detroit Diesel Customer Support Center at 313–592–5800.