Cummins/Onan — Replacing Fuel Filter
Maintenance · Fuel system
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDDC, John Deere 4045TFM engine, John Deere 6068TFM engine
Before you start
- Diesel fuel is combustible; keep ignition sources away.
- Disconnect negative battery cable to prevent accidental starting.
Parts for this job
- 149-2106 Fuel filter — Cummins/Onan MDDC Amazon eBay $34.99 NAPA $61.61 KuduParts $68.00
- DQ24057 Fuel filter — John Deere 4045TFM engine Amazon eBay $19.49
Part numbers from the service-parts lists for Cummins/Onan MDDC, John Deere 4045TFM engine. Verify against your serial number before ordering; some links are affiliate links.
Procedure
- Disconnect negative battery cable and close fuel supply and return valves.
- Disconnect the water sensor.
- Clean area around each filter and drain fuel from each filter by loosening vent and drain screws.
- Grasp each filter retaining ring, lift and rotate counterclockwise 1/4 turn; remove ring with element.
- Install new filters indexing raised locators with base slots.
- Install retaining rings with dust seals in place; hand tighten about 1/3 turn until it snaps into detent.
- Reconnect water sensor and negative battery cable.
- Prime engine with mechanical priming lever or electric pump for at least 30 seconds.
- Run generator a few minutes and check for leaks.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Hand tighten retaining ring about 1/3 turn until it snaps
Full service-parts list: Cummins/Onan MDDC →, John Deere 4045TFM engine →
Source: Cummins/Onan owner'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.