TESTING AND ADJUSTING
5. SUDDEN CHANGES IN ENGINE SPEED (rpm)
Failure of Governor or Fuel Injection
Look for damaged or broken springs, linkage or other parts. Remove
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.
Air In The Fuel System
Fuel Pressure Is Low
Bad Quality Fuel
Constant Bleed Valve Stays Open or
Leaks in Air Inlet System
Wrong Valve Clearance
Defect in Fuel Injection Valve(s) or
Fuel Injection Pump(s)
Wrong Fuel Injection Timing
Rack Setting Too Low
Turbocharger Has Carbon Deposits
or Other Causes of Friction
6. NOT ENOUGH POWER
Find air leak in the fuel system and correct. Remove air from fuel
system. See FUEL SYSTEM in Testing and Adjusting.
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
fuel bypass valve and the check valves in the fuel transfer pump.
Remove the fuel from the fuel tank. Install a new fuel filter element.
Put a good grade of clean fuel in the fuel tank.
Install new parts if needed.
Check the pressure in the air inlet manifold. Look for restrictions in
the air cleaner.
Make adjustment to get full travel of linkage. Install new parts for
those that have damage or defects.
Make adjustment, See the Subject VALVE CLEARANCE in Test-
ing and Adjusting.
Run 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 does
not change the way the engine runs. Test the injection pump and
injection valve for that cylinder. Install new parts where needed.
Make adjustment to timing.
Make reference to FUEL SYSTEM in Testing and Adjusting.
Make inspection and repair of turbocharger as necessary.