SPRING 2697050 - 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
Contamination in the check valves for the fuel priming pump
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
Contamination 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 lineChecking 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 g00293196
1U-5470 Engine Pressure Group
Refer to Special Instruction, SEHS8907, "Using The 1U-5470 Engine Pressure Group" for more information. Refer to Operating Manual, NEHS0818, "Using the 198-4240 Pressure Indicator Tool Group" for more information.
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. Clean up fuel spills immediately.
Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.Dispose of all fluids according to local regulations and mandates.
Illustration 2 g03153417
C9.3 fuel transfer pump mounted on the high-pressure fuel pump
Illustration 3 g03122401
C9.3 fuel transfer pump
(4) Low-pressure fuel inlet
(5) Low-pressure fuel outlet
(6) Pressure regulating valve
Illustration 4 g02928276
C13 - C18 fuel transfer pump
(4) Low-pressure fuel outlet
(5) Low-pressure fuel inlet
(6) Pressure regulating valve
Use the following procedure to check the output of the fuel transfer pump:
Remove the fuel line (4).
Tee the 1U-5470 Engine Pressure Group into the port that contained the fitting for the fuel line (4) .
Adjust the engine speed to 600 rpm with no load.
The fuel pressure should be 690 kPa (100 psi) to 724 kPa (105 psi).
If the fuel pressure is within the specified range, proceed to Step 3.
If the pressure is less than 655 kPa (95 psi), the fuel transfer pump is weak. The pressure regulating valve (6) in the pump may be stuck or worn. Remove the pressure regulating valve, the spring, and the pin. Inspect the pressure regulating valve. If contamination is not found, and the pressure regulating valve is worn out, replace the fuel transfer pump. If dirt is found, clean the valve assembly and reinstall the valve assembly.
Check the fuel pressure again. Replace the fuel transfer pump if the