Fuel Injectors & Pumps – Section 3.2 MBE 900 Unit Pump Inspection/Removal

Section 3.2
MBE 900 Unit Pump Inspection/Removal

To determine if the unit pump and nozzle are not functioning properly and need 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.

Folow the service manual procedures to remove the unit pump:‪

1. Remove engine trim cover.
2. Remove the end cover from the lower right side of the flywheel housing, then attach the engine barring tool (J-46392).
3. Remove the fuel injection line.
4. Disconnect the engine wiring harness from each injector unit pump to be removed.
5. Carefully loosen the injector unit pump mounting bolts.
6. Check the spring tension on the injector unit pump by pushing down on it. If you cannot push down on the injector pump manually, the spring tension is at the maximum. You must decrease the spring tension on the injector pump before removing it.
7. Using the barring tool (J-46392) , rotate the crankshaft until the spring tension decreases enough to push the injector pump down manually.
8. Remove the mounting bolts from the injector unit pump.
9. Using the barring tool, rotate the crankshaft until the camshaft lifts the injector unit pump.
10. If the injector unit pump does not come out easily, use the injector/unit pump puller tool (J-46375) to remove it.
11. Thread the impact extractor onto the top of the injector unit pump, where the injection line was installed.
12. Pull the injector unit pump out by using the slide hammer on the impact extractor. Do not use excessive force that could damage the threads on the injector unit pump fuel line connection.

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

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

1. Remove the engine trim panel and cylinder head cover.
2. Remove the injection line using injection line socket (J-46371) .
3. Remove the transfer tube. Discard the old O-ring.
4. Remove the tensioning arm.
5. Attach the adapter tool J-46384 and impact extractor tool (J-46375) . Thread the narrow end of the adaptor onto the internal threading in the head of the nozzle holder. Thread the impact extractor onto the wide end of the adaptor.
6. Using the impact extractor, pull out the nozzle holder.
7. Take the heat isolator off the nozzle holder.

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