Cummins/Onan — Fuel/Water Separator Drain
Maintenance
From a Cummins/Onan operator's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DFEJ, Cummins/Onan DFEK, Cummins/Onan QSX15-G9 engine
Before you start
- Do not over tighten the valve; over tightening can damage the threads.
- Dispose of drained liquids per local environmental regulations.
Procedure
- Shut off the engine.
- Place a suitable container under the fuel filter.
- With the fuel supply valve closed, open the vent cap to break the airlock.
- Turn the valve counterclockwise until the valve drops about one inch (25 mm).
- Drain the filter sump until clear fuel is visible.
- Push the valve up and turn clockwise to close the drain valve.
- Open the fuel supply valve before starting the engine.
- If more than 2 oz (60 ml) is drained, refill the filter to prevent hard starting.
Tools required
- Suitable container Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Drain valve drop about 1 inch (25 mm)
- Refill filter if more than 2 oz (60 ml) drained
Full service-parts list: Cummins/Onan DFEJ →, Cummins/Onan DFEK →
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.