Cummins/Onan — Fuel Pump Reconditioning
Repair & overhaul
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Use care when reassembling and reinstalling the pump. Improper parts alignment or misconnected fuel lines may result in leaking fuel, creating a serious fire hazard.
Procedure
- Remove fuel lines and mounting screws holding pump to engine.
- Make indicating mark across fuel pump bolt and cover for reassembly.
- Remove assembly screws and remove upper pump body.
- Remove valve plate screw and washer; remove valve retainer, valves, valve springs, and valve gasket; discard springs, valves, and retainer gasket.
- Clean pump body thoroughly with solvent and fine wire brush.
- Place new valve gasket into cavity; assemble valve spring and valves; reassemble valve retainer and tighten screw.
- Press down on diaphragm to compress spring, turn bracket 90 degrees to unhook diaphragm for removal.
- Clean mounting bracket with solvent and fine wire brush.
- Replace diaphragm, fuel pump rod spring, diaphragm gasket; stand new spring in casting, position diaphragm, compress spring, turn 90 degrees to reconnect.
- Place pump cover on bracket, align marks, insert four screws; do not tighten.
- Push pump lever to limit of travel and hold while tightening four screws.
- Mount fuel pump on engine using new mounting gaskets; connect fuel lines.
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.