T R O U B L E S H O O T I N GTM 5-3805-258-24-1T E S T I N G A N D A D J U S T I N GCauseAir In The Fuel SystemFuel Pressure is LowLeak or Break in Fuel Line BetweenInjection Pump and Injection Valve3. MISFIRING OR RUNNING ROUGHDefect in Fuel Injection Valve(s) orInjection Pump(s)Fuel System Not Timed Correctly toEngineWrong Valve ClearanceBent or Broken Push RodWorn Valve Seat or Face of ValveCorrectionFind air leak in the fuel system and correct. Remove air from fuelsystem. See FUEL SYSTEM in Testing and Adjusting.Make sure there is fuel in the fuel tank. Look for leaks or bad bends inthe fuel line between fuel tank and fuel transfer pump. Look for air inthe fuel system. Check fuel pressure at the fuel injection pumphousing. If fuel pressure at high idle is lower than 105 kPa (15 psi),install a new filter element. If fuel pressure is still low, check the fuelbypass valve and the check valves in the fuel transfer pump.Install a new fuel line.Run engine at rpm that gives maximum misfiring or rough running.Then loosen a fuel line nut on the injection valve for each cylinder,one at a time. Find the cylinder where loosening the fuel line nut doesnot change the way the engine runs. Test the injection pump andinjection valve for that cylinder. Install new parts where needed.Make adjustment to timing if necessary.Make adjustment, See the Subject VALVE CLEARANCE in Test-ing and Adjusting.Replacement of push rod is necessary.Reconditioning of cylinder head is needed.CauseIdle rpm Too LowDefect in Fuel InjectionFuel Injection Pump(s)4. STALL AT LOW RPMCorrectionMake adjustment to governor so idle rpm is the same as given in theFUEL SETTING INFORMATION.Valve(s) orRun engine at rpm that gives maximum misfiring or rough running.Then loosen a fuel line nut on the injection pump for each cylinder,one at a time. Find the cylinder where loosening the fuel line nut doesnot change the way the engine runs. Test the injection pump andinjection valve for that cylinder. Install new parts where needed.4-85
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