DISC-KIT 8U9541 - 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 (if equipped)
Sticking or worn fuel pressure regulating valve in the fuel transfer pump
Severe wear on return fuel pressure regulating valve at the rear of the cylinder head
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 lineChecking Fuel Pressure
Illustration 1 g00293196
1U-5470 Engine Pressure Group
Refer to Special Instruction, SEHS8907, "Using The 1U-5470 Engine Pressure Group".
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, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Use the following procedure to measure the fuel pressure after the secondary filter:Note: Fuel pressure readings near the fuel supply manifold have pressure spikes. The pressure spikes are caused by excess fuel that is returning to the fuel system from the injectors. Excessive needle movement at the gauge may be present. Connect the gauge with a section of suitable hose. The air in the hose absorbs the spikes. This gives an average reading and a steady needle. Keep the gauge above the measuring point.
Illustration 2 g01130021
(1) Plug Install the 1U-5470 Engine Pressure Group into port (1).During both normal operating conditions and load conditions, the fuel pressure should register the following range:
455 to 579 kPa (66 to 84 psi)At low idle, the fuel pressure at the fuel filter's inlet should be at the following amount:
400 to 434 kPa (58 to 63 psi)The fuel pressure to the fuel gallery should be the same amount, if you subtract the change in pressure (delta P) across the filter. With a new filter, the pressure drop across the fuel filter typically registers the following amount:
35 kPa (5 psi)As deposits collect on a fuel filter, the pressure differential will increase. Engine misfire may occur if the fuel pressure in the fuel gallery decreases to approximately 69 kPa (10 psi).The fuel pressure regulator valve is mounted at the