Northern Lights — Bleeding the Fuel System
Maintenance
From a Northern Lights owner's manual covering: L439, L668, M40C, M439, M445, M65C, M668, M99C. Check it applies to your exact model before use.
Applies to: Northern Lights M668
Before you start
- Escaping diesel fuel under pressure can penetrate the skin; use cardboard or wood, not hands, to search for leaks.
- Always use a backup wrench when loosening or tightening fuel lines.
Procedure
- Loosen bleed plug on the fuel filter cartridge.
- Operate primer pump lever on fuel transfer pump until most air bubbles expelled.
- Tighten bleed plug.
- If engine will not start, loosen fuel supply pipe at pump and prime until fuel free of air.
- Retighten fuel supply line to 22 ft. lb. (30 N·m).
- If still no start, loosen fuel line at injection nozzle, crank engine until fuel without air flows, tighten to 20 foot lb. (27 N·m).
Tools required
- Backup wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Fuel supply line 22 ft. lb. (30 N·m)
- Nozzle line connection 20 foot lb. (27 N·m)
Full service-parts list: Northern Lights M668 →
Source: Northern Lights 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.