TROUBLESHOOTING
TESTING AND ADJUSTING
5. SUDDEN CHANGES IN ENGINE SPEED (rpm)
Cause
Correction
Failure of Governor or Fuel Injection
Look for damaged or broken springs, linkage or other parts. Remove
Pump
the governor. Check for free travel of the fuel rack. Be sure fuel
injection pumps are installed correctly. Check for correct governor
spring. Install new parts for those that have damage or defects.
6. NOT ENOUGH POWER
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 fuel filter element. If fuel pressure is still low, check the
pumping spring and the check valves in the fuel transfer pump.
Bad Quality Fuel
Remove the fuel from the fuel tank. Install a new fuel filter element.
Put a good grade of clean fuel in the fuel tank.
Constant Bleed Valve Stays Open or
Install new parts if needed.
Closed
Leaks in Air Inlet System
Check the pressure in the air inlet manifold. Look for restrictions in
the air cleaner.
Governor Linkage
Make adjustment to get full travel of linkage. Install new parts for
those that have damage or defects.
Wrong Valve Clearance
Make adjustment. See the Subject VALVE CLEARANCE in Test-
ing and Adjusting.
Defect in Fuel Injection Valve(s) or
Run engine at rpm that gives maximum misfiring or rough running.
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.
Wrong Fuel Injection Timing
Make adjustment to timing.
Rack Setting Too Low
Make reference to the FUEL SETTING AND RELATED IN-
FORMATION FICHE.
Turbocharger Has Carbon De-
Make inspection and repair of turbocharger as necessary.
posits or Other Causes of Friction
