Cummins/Onan — Injection Pump Timing - Method 2 (Flowing the Pump)

Adjustments

From a Cummins/Onan service manual — check it applies to your exact model before use.

Applies to: Cummins/Onan DJB engine

Procedure

1. Install a standard timing button and install the pump.
2. Remove the delivery valve cap screw and lift out the spring and delivery valve.
3. Rotate the flywheel counterclockwise to about 15 degrees before the port closing mark.
4. Set the throttle lever wide open and connect lines; prime to obtain fuel pressure.
5. Slowly rotate flywheel clockwise until fuel stops flowing from number 1 injection line (port closing).
6. Check the timing pointer; select proper button from Table 2 if not coinciding.
7. Remove pump, insert proper button, reinstall and recheck port closing.
8. Replace delivery valve disassembly and torque to 75-80 ft-lb.

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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