HOSE AS 3749966 - 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 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
The typical fuel pressure of the engine at operating temperature should between 446 34 kPa (65 5 psi) to 894 34 kPa (130 5 psi).The performance of the unit injector deteriorates when the fuel pressure drops below 446 34 kPa (65 5 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
3Y-2888 Connector 1
3J-1907 O-Ring Seal 1
Illustration 1 g00294866
1U-5470 Engine Pressure Group
Illustration 2 g01098018
(1) Typical locations of fuel pressure tapsTo check the fuel transfer pump pressure, remove the plug from the fuel filter base. Install the 3Y-2888 Connector with a 3J-1907 O-Ring Seal. Install a pressure gauge, and start the engine.The 1U-5470 Engine Pressure Group can be used in order to check the fuel pressure of the engine. The engine pressure group includes Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group". This instruction provides information about the usage of the group.