Cummins/Onan 6.5NH - 3CR / 6000 A — Fuel Pump Reconditioning
Repair & overhaul · Mechanical diaphragm fuel pump
For the Cummins/Onan 6.5NH - 3CR / 6000 A, from the Cummins/Onan service manual.
Applies to: Cummins/Onan NH engine
Before you start
- When checking the fuel pump always direct fuel into a container. Do not spill fuel on ignition wires.
Procedure
- Remove fuel lines and mounting screws holding the pump to the engine.
- Mark a line across the union of pump body and cover to assure proper reassembly; remove assembly screws and upper pump body.
- Turn the pump body over, remove valve cage screw and washer, valve retainer, valves, valve springs and valve gasket; discard springs, valves and retainer gasket.
- Clean the pump body thoroughly with solvent and a fine wire brush.
- Place a new valve gasket in the cavity; assemble valve spring and valves, reassemble the valve retainer and lock with the retainer screw.
- Rebuild the lower diaphragm section.
- Hold the mounting bracket, press down on the diaphragm to compress the spring, turn bracket 90 degrees to unhook the diaphragm.
- Clean the mounting bracket with solvent and a fine wire brush.
- Replace the diaphragm operating spring, position the diaphragm, press down and turn 90 degrees to reconnect.
- Place the pump cover on the bracket with marks in line, insert four screws but do not tighten.
- Push the pump lever to the limit of travel and hold while tightening the four screws; mount pump with new gaskets and connect fuel lines.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.