Cummins/Onan 4MCCK / 605MCCK — Fuel Pump Assembly
Repair & overhaul
For the Cummins/Onan 4MCCK / 605MCCK, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 605MCCK, Cummins/Onan MCCK, Cummins/Onan MCCK engine
Before you start
- The diaphragm must be flexed, or it will deliver too much fuel pressure.
Procedure
- Soak the diaphragm in fuel; insert the diaphragm spring and soaked diaphragm into the pump body.
- Insert the link and rocker arm into the body and hook it over the diaphragm pull rod.
- Align the rocker arm with the pin hole and drive in the pin.
- Compress the rocker spring and install it between the body and rocker arm.
- Insert the valve cages, gaskets and valve cover plate.
- Assemble the cover to the body with scribed marks aligned; install screws but do not tighten.
- Push the rocker arm to full stroke and hold in this position to flex the diaphragm.
- Tighten cover screws alternately and securely before releasing the rocker arm.
- Install the pump and repeat the pressure test.
Full service-parts list: Cummins/Onan 605MCCK →, Cummins/Onan MCCK →
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.