COVER 2M8361 - Caterpillar

Low Fuel Pressure
Low fuel pressure can cause low power. Low fuel pressure can also cause cavitation of the fuel which can damage the fuel injectors. The following conditions can cause low fuel pressure:
Plugged fuel filters
Debris in the check valves for the fuel priming pump
Debris in the fuel pressure regulating valve
Partially open check valve
Sticking or worn fuel pressure regulating valve in the fuel transfer pump
Severe wear on return fuel pressure regulating valve in the fuel filter base
Worn gears in the fuel transfer pump
Pinched fuel lines or undersized fuel lines
Old fuel lines that have a reduced interior diameter that was caused by swelling
Fuel lines with deteriorating interior surfaces
Pinched fuel line fittings or undersized fuel line fittings
Debris in the fuel tank, fuel lines, or fuel system components that create restrictionsHigh Fuel Pressure
Excessive fuel pressure can cause fuel filter gaskets to rupture. The following conditions can cause high fuel pressure:
Plugged orifices in the fuel pressure regulating valve
Stuck fuel pressure regulating valve in the fuel transfer pump
Pinched fuel return lineFuel Pressure Readings
Different configurations are used for the low-pressure side of the fuel system. The different configurations cause different fuel pressure readings.Lower Fuel Pressure Configuration
The typical fuel pressure of the engine at operating temperature can vary. With new fuel filters, the fuel pressure at the secondary fuel filter base must be within the following ranges. At cranking speed (100-135 rpm), the fuel pressure can be 75 kPa (11 psi). At low idle (700 to 900 rpm), the fuel pressure can be 450 50 kPa (65 7 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 500 50 kPa (73 7 psi).The performance of the unit injector deteriorates when the fuel pressure drops below 390 kPa (57 psi). Low-power complaints and erratic operation can occur in this situation. Check for a plugged fuel filter or air in the fuel lines as possible causes for these complaints before replacing fuel system components.Higher Fuel Pressure Configuration
The typical fuel pressure of the engine at operating temperature can vary. With new fuel filters, the fuel pressure at the secondary fuel filter base must be within the following ranges. At cranking speed (100-135 rpm), the fuel pressure can be 75 kPa (11 psi). At low idle (700 to 900 rpm), the fuel pressure can be 650 50 kPa (94 7 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 705 50 kPa (102 7 psi).The performance of the unit injector deteriorates when the fuel pressure drops below 390 kPa (57 psi). Low-power complaints and erratic operation can occur in this situation. Check for a plugged fuel filter or air in the fuel lines as possible causes for these complaints before replacing fuel system components.Checking Fuel Pressure
Table 1
Required Tools
Part Number Part Name Quantity
1U-5470
or
198-4240 Engine Pressure Group
or
Digital Pressure Indicator 1
Illustration 1 g00294866
1U-5470 Engine Pressure Group
To check the fuel pressure, remove the elbow from the fuel filter base. Install the pressure gauge and appropriate fittings from the