Cummins/Onan — Priming the Low-Pressure Fuel System
Maintenance
From a Cummins/Onan operator's manual covering: MDKAD 10, MDKAD 12.5, MDKAE 16, MDKAE 20, MDKAF 20, MDKAF 25. Check it applies to your exact model before use.
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Before you start
- Depressing the start/stop switch in stop/preheat mode longer than 15 seconds can cause premature failure of the glow plugs.
- Dispose of fuel in an approved, environmentally safe location.
- Do not permit any flame, spark, or other ignition source near the fuel system.
Procedure
- Place a large (1 quart) container under the fuel return connection.
- If the fuel supply line or fuel filter is completely dry, disconnect the glow plug lead and shield the terminal with tape.
- MDKAD/MDKAE only: open the air vent valve by turning it counterclockwise until completely open.
- Push the start/stop switch to the stop position and hold for 15 seconds or until a steady stream of fuel is observed at the return connection.
- Release the start/stop switch.
- MDKAD/MDKAE only: close the air vent valve by turning it clockwise until completely closed.
- Reconnect the glow plug lead if it was disconnected.
- Reconnect the fuel return line in its original configuration.
- Start the generator set and check for normal operation and leaks.
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.