Cummins/Onan — Bleeding the Fuel System
Maintenance
From a Cummins/Onan operator's manual covering: 12.0MDJF-53CR, 12.0MDJF-53CR4, 12.0MDJF-54R, 12.0MDJF-55DR, 12.0MDJF-57R, 15.0MDJ F .. .4R 196 D, 15.0MDJF, 15.0MDJF-3CR, 15.0MDJF-3CR4, 15.0MDJF-5DR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 12.0MDJF-53CR, Cummins/Onan MDJF (Onan J-series diesel) engine, Cummins/Onan MDJF engine
Procedure
- Disconnect the fuel return line.
- Operate the hand priming lever on the diaphragm type fuel transfer pump until no air bubbles flow from the injection pump return fitting.
- Connect the fuel return line.
- If the camshaft pump lobe is up, crank the engine one revolution.
- Return the priming lever inward (disengaged) to permit normal pump operation.
Full service-parts list: Cummins/Onan 12.0MDJF-53CR →
Source: Cummins/Onan operator's 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.