TROUBLESHOOTING
TESTING AND ADJUSTING
3. MISFIRING OR RUNNING ROUGH
Cause
Correction
Air In The Fuel System
Find air leak in the fuel system and correct. Remove air from fuel
system. See FUEL SYSTEM in Testing and Adjusting.
Fuel Pressure is Low
Make sure there is fuel in the fuel tank. Look for leaks or bad bends
in the fuel line between fuel tank and fuel transfer pump. Look for
air in the fuel system. Check fuel pressure at the fuel injection pump
housing. 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
pumping spring and the check valves in the fuel transfer pump.
Leak or Break in Fuel Line Between
Install a new fuel line.
Injection Pump and Injection Valve
Defect in Fuel Injection Valve(s) or
Run engine at rpm that gives maximum misfiring or rough running.
Injection Pump(s)
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 does
not change the way the engine runs. Test the injection pump and
injection valve for that cylinder. Install new parts where needed.
Fuel System Not Timed Correctly to
Make adjustment to timing if necessary.
Engine
Wrong Valve Clearance
Make adjustment, See the Subject VALVE CLEARANCE in Test-
ing and Adjusting.
Bent or Broken Push Rod
Replacement of push rod is necessary.
Worn Valve Seat or Face of Valve
Reconditioning of cylinder head is needed.
4. STALL AT LOW RPM
Cause
Correction
Idle rpm Too Low
Make adjustment to governor so idle rpm is the same as given in the
FUEL SETTING AND RELATED INFORMATION FICHE.
Defect in Fuel Injection Valve(s)
Run engine at rpm that gives maximum misfiring or rough running.
or Fuel Injection Pump(s)
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 does
not change the way the engine runs. Test the injection pump and
injection valve for that cylinder. Install new parts where needed.
