Cummins/Onan — Bleeding Fuel System (Begin Spec S)
Maintenance · Diesel fuel system
From a Cummins/Onan service manual covering: 2.5A, 2.5L, 2.7 AJ, 4.0CCK, 6.0CCKB, 6.5 NH, JC - 3CR / 96 T. Check it applies to your exact model before use.
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Before you start
- If the camshaft pump lobe is up, crank engine one revolution to permit hand priming.
- Return priming lever inward to disengaged position when finished.
Procedure
- Disconnect the fuel return line.
- Operate the hand priming lever on the diaphragm fuel transfer pump until no air bubbles flow from the return line fitting.
- Reconnect the fuel return line.
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.