.,. TM  5-5420-226-20-1 Symptom-2 DETAILED TROUBLESHOOTING PROCEDURE . . VEHICLE OPERATION -  POWERPLANT, STARTING T (Continued) m Check for   free    fuel   flow    to   the   inlet   side    of   the backflow valve. Y First Technician (Rear of   Crew Compartment) l   Tighten primary fuel   filter bleed  valve. , l   Remove    lower   engine   access   panel    (page    17-16). l   Disconnect main fuel   line    from backflow valve    inlet (page 7-25). l   Place   a   container or    rags    under main fuel   line    to catch any    fuel. Second Technician (Operator’s Station) l   Set   MASTER BATTERY switch ON. l   Set   FUEL PUMPS switch ON for   approximately 10 seconds then set   FUEL PUMPS switch OFF. l   Set   MASTER BATTERY switch OFF. First Technician (Rear of  Crew    Compartment) l   Check    for   free   fuel    flow    from   main   fuel   line. ( Did   fuel   flow    freely from    main   fuel    line   to   the backflow valve? m OUTLET I BACKFLOW VALVE l   Clear    line   between primary fuel   filter    and   backflow valve by   blowing with   compressed air. l   Connect main   fuel   line   to backflow valve iniet (page 7-27). l   If  this   does    not   work,    replace fuel   line   (page 7-40). TA106821 4-132