Cummins/Onan — External Fuel Filter Change
Maintenance · External fuel filter (Fuel Pro)
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
- For Biodiesel applications use gasket pack 3950445 S; green gasket MUST be changed with every filter change.
- Do not overtighten fuel lines or fuel line fittings.
Procedure
- Turn off the engine; loosen the vent cap to break the air lock in the filter.
- Open the drain valve and drain fuel below the collar, then close the valve.
- Using the collar/vent cap wrench, remove the collar and clear cover; discard the o-ring.
- Remove the filter element by pulling upward and twisting slightly.
- Install the new element on the center stud by pushing down and twisting slightly.
- Install the cover and collar; hand tighten until seated; do not use tools.
- Fill the clear cover with clean fuel to cover the bottom half of the element.
- Start the engine; at normal oil pressure increase RPM for one minute.
Tools required
- Collar/Vent Cap Wrench 3944451 S (plastic) or 3944448 S (metal) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Filter element changed when fuel level rises to top of element
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.