Cummins/Onan — Fuel Supply Lines - Vent (Low-Pressure Lines and Fuel Filter)
Maintenance · fuel system
From a Cummins/Onan owner's manual covering: 4B3.9, 4BT 3.9, 4BTA 3.9, 6B5.9, 6BT 5.9, 6BTA5.9, B3.9, B5.9, C8.3. Check it applies to your exact model before use.
Applies to: Cummins/Onan 4B3.9, Cummins/Onan 6BTA5.9, Cummins/Onan B5.9 engine
Procedure
- Open the vent screw.
- Operate the priming button on the lift pump until the fuel flowing from the fitting is air free.
- Tighten the bleed screw to 9 N*m [80 in-lb].
Tools required
- 8 mm wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Bleed screw Torque Value: 9 N*m [80 in-lb]
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.