Cummins/Onan — Fuel Line Installation and Routing
Installation · Fuel supply/return lines
From a Cummins/Onan service manual covering: 5.5 HGJAA, 5.5 HGJAB, 5.5 HGJAC, 6.5 HGJAA, 6.5 HGJAB, 6.5 HGJAC, 7.0 HGJAA, 7.0 HGJAB, 7.0 HGJAC. Check it applies to your exact model before use.
Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAC
Before you start
- Electric arcs can ignite gasoline leading to severe personal injury or death. Do not run wiring and fuel lines together.
Procedure
- Use 5/16 inch O.D. (supply) or 1/4 inch O.D. (return) welded and drawn Type 304L stainless or AISI 1008−1010 low carbon steel tubing, 0.028 inch minimum wall thickness.
- Form tubing ends into SAE J1231 Type 1 or Type 3 double-flare hose beads.
- Use flexible hose meeting SAE J30R9 for working pressure and evaporative emissions.
- Use stainless steel stepless ear clamps.
- Route supply and return lines side-by-side along bulkheads and frame members, at or above the top of the fuel tank.
- Support fuel lines to restrain movement and prevent chaffing or contact with sharp edges, electrical wiring and hot exhaust parts.
Tools required
- Tubing bender/flaring tooling for SAE J1231 hose beads Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Tubing must meet 150 psi operating pressure (Ref. ASTM A 539−99)
- Maximum fuel pump lift 36 inches (914 mm)
Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAC →
Source: Cummins/Onan service 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.