TM  5-5420-226-20-1 Symptom-2 DETAILED TROUBLESHOOTING PROCEDURE VEHICLE OPERATION -  POWERPLANT, STARTING (Continued) I Check for   fuel   flow    at   main    fuel    return line   quick disconnect. Second Technician (Operator’s Station) l   Set   MASTER BATTERY switch OFF. Both Technicians (Rear Grille Doors) l First l l l Remove transmission shroud (page    9-2). Technician (Rear Grille Doors) Disconnect main fuel   return line   quick disconnect. Remove quick disconnect half   from fuel   line   coming from engine. Place    one   gallon container under open    line   to   catch any   fuel. Second Technician (Operator’s Station) l   Set   MASTER BATTERY switch ON. l   Set   FUEL PUMPS switch ON. First Technician (Rear Grille Doors) l   Observe    return line   for   free   fuel   flow. l   Direct    second    technician to   set   MASTER BATTERY and    FUEL PUMPS switches OFF. f’- .=- MAIN h FUEL RETURN LINE    QUICK DISCONNECT FITTING’ — REAR    OF   ENGINE (TRANSMISSION SHROUD REMOVED) Does    fuel   flow    freely from    main   fuel   return line? TA106813 ‘o    Check for   free    fuel   flow    from main   fuel   supply line   quick disconnect (located behind upper engine access panel). 4-124