5032952 JOHNSON NUT

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.
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
Sticking or worn fuel pressure relief valve in the fuel transfer pump
Severe wear on return fuel pressure regulating valve in the fuel filter base or adapter assembly
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 may 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 relief valve in the fuel transfer pump
Pinched fuel return lineChecking Fuel Pressure
Table 1
Required Toolings
Tool Part Number Part Name Quantity
A 1U-5470
or
198-4240 Engine Pressure Group
or
Digital Pressure Indicator 1
Illustration 1 g00293196
1U-5470 Engine Pressure Group
Reference: Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group"Reference: Operation Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator"Fuel System Identification
Refer to the following illustrations in order to identify the fuel system for your application. Locate the pressure testing ports in order to measure the different fuel system pressures.
Illustration 2 g00996187
Fuel filter base that is mounted directly to the fuel manifold
Typical example
(1) Test location for unfiltered fuel pressure
(2) Test location for filtered fuel pressure
Illustration 3 g00996311
Applications with a fuel adapter
Typical example
(1) Test location for unfiltered fuel pressure
(2) Test location for filtered fuel pressure Applications with a Quick Connect Coupler
Some applications may be equipped with a quick connect coupler. Refer to these illustrations for the location and the purpose of the fuel pressure tap.
Illustration 4 g00996062
Fuel filter base that is mounted directly to the fuel manifold
Typical example
(1) Test location for unfiltered fuel pressure
(2) Test location for filtered fuel pressure
Illustration 5 g00996149
Applications with a fuel adapter
Typical example
(1) Test location for unfiltered fuel pressure
(2) Test location for filtered fuel pressure Measuring Unfiltered Fuel Pressure
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. Clean up fuel spills immediately.
A high pressure fuel line must be disconnected. To avoid personal injury or fire from fuel spray, the engine must be stopped before the fuel line is disconnected.
Use the following procedure to measure the unfiltered fuel pressure:
Refer to "Fuel System Identification" in order to identify the correct location for measuring the unfiltered fuel pressure. Install Tooling (A) into pressure test location (1) in order to measure the unfiltered fuel pressure. Note: A fuel sensor may be installed in one of the ports that are indicated in the illustrations. If a fuel se