Fuel Injectors & Pumps – Section 3.3 MBE 4000 Unit Pump Inspection/Removal

Section 3.3
MBE 4000 Unit Pump Inspection/Removal

To determine if the unit pump and nozzle is not functioning properly and needs to be replaced, follow this procedure:‪

1. Drain fuel system and remove unit pump. If necessary, remove nozzle.
2. Wipe oil off unit pump.
3. Inspect unit pump and nozzle for leaks, turned O-rings, seized pump, cracked body, or failed/ blown spray nozzle.

Follow the service manual procedure to remove the unit pump:‪

1. Remove the engine trim cover.
2. Unscrew the fuel filter cap.
3. Disconnect the engine wiring harness from the injector unit pump.
4. Remove the high-pressure fuel injector line.
5. Disconnect the fuel line at the fuel gallery inlet. Use suitable container to catch any fuel that comes out of the cylinder block or fuel line.
6. Drain the fuel from the engine through the fuel gallery outlet on the return lines.
7. Remove the end cover from the lower right side of the flywheel housing, then attach the engine cranking tool (J-46167) .
8. Carefully loosen the injector unit pump mounting bolts about 6 mm (0.25 inch), but do not remove them yet.
9. Using the cranking tool number (J-46167) , rotate the crankshaft until the cam pushes the unit pump upwards.
10. Remove mounting bolts and carefully pull unit out of cylinder block. Discard O-rings.

Note: If the injector unit pump is locked up, or frozen in its seat, release it using the blade of a small screwdriver on the flange where the mounting bolt attaches.

If nozzle and holder needs to be removed, follow this procedure:‪

Note: Do not attempt to take apart the nozzle. If there is a problem, replace the nozzle.

1. Remove the engine trim cover and cylinder head cover for each cylinder head.
2. Remove the charge-air manifold.
3. Remove the injector line.
4. Remove the thrust bolt and the transfer tube. Discard the old O-ring.
5. Remove the tensioning arm.
6. Attach the impact extractor tool (J-46375) and adaptor tool (J-46384) . Thread the narrow end of the adaptor onto the internal M8 threading in the head of the nozzle. Thread the impact extractor onto the wide end of the adaptor.
7. Using the impact extractor tool (J-46375) , remove the nozzle from the cylinder head. Discard the O-ring and seal ring.
8. Cap off or cover the openings in the fuel lines to prevent contamination of the fuel.

Note: For current information on removal and installation of unit pump or nozzle, refer to MBE 900 service manual (6SE414) or MBE 4000 service manual (6SE412).