* Fuel Pressure Is Low
* Engine Accessories
* Defect In Unit Injector(s)
* Air In Fuel
* Incorrect fuel grade
* Combustion Gas, Or Water In Fuel
* Loss of pressure in high pressure hydraulic oil system
1. 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. Make sure the fuel filters are clean, then check fuel pressure. Engine fuel pressure while cranking should read between 275 to 350 kPa (40 to 50 psi). At low idle, fuel pressure should read between 400 to 435 kPa (58 to 63 psi), and at normal operating conditions under load, fuel pressure should read between 400 and 525 kPa (58 to 76 psi). If fuel pressure is lower than the above pressure, check the fuel transfer pump and fuel pressure regulating orifice at the fuel return line.
2. Engine accessories:
Check engine accessories for damage and make repair or replacement. If necessary, disconnect the accessories and test the engine.
3. Defect in Unit Injector(s):
Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injector Solenoid Circuit Test.
4. Air in fuel:
Check inlet fuel line or transfer pump for leaks by installing a sight glass on the fuel return line. Repair as needed or install new components.
5. Incorrect fuel grade:
Check fuel grade. In cold weather below 0.0°C (32°F), make sure that winter grade fuel is being used. Check for waxing.
6. Combustion gas, or water in fuel:
Check unit injector sleeves. Repair as needed or install new components.
7. Loss of pressure in high pressure hydraulic oil system:
Refer to problem 3: Engine hard to or will not start. Engine crankshaft turns freely.