Probable Cause:
1. Fuel Pressure Is Low
Make sure there is enough fuel in the fuel tank. Look for leaks or severe bends in the fuel line between fuel tank and fuel transfer pump. Look for air in the fuel system. Check fuel pressure. The outlet pressure of the fuel transfer pump at full load speed is 205 ± 35 kPa (30 ± 5 psi). If fuel pressure is lower than above pressure, install a new fuel filter element. Inspect the bypass valve for free movement. Install a new bypass valve if necessary.
2. Idle rpm Too Low
Make adjustment to governor so idle rpm is the same as given in the TMI (Technical Marketing Information) or Fuel Setting And Related Information Fiche.
3. Defect In Fuel Injection Nozzle
Install a new fuel injection nozzle.
4. Wrong Valve Lash
Make adjustment according to Testing & Adjusting.
5. Spring For Dashpot Governor Installed Wrong
Install spring correctly.