91309-ZV5-821 Honda O-RING (Honda Code 4594859).

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, PERJ1017, "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.
Specifications
Table 1
Fuel Pressure after the Secondary Filter
RPM Pressure Specification
1800 586 kPa (85 psi)
Table 2
Fuel Pressure at Output of the Fuel Transfer Pump
RPM Pressure Specification
600 690 kPa to 724 kPa (100 psi to 105 psi)
Table 3
Vacuum at the Primary Filter
Outlet Specification Vacuum Difference between Inlet and Outlet
10.14 kPa to 13.52 kPa (3 inch mercury to 4 inch mercury) Less than 3.38 kPa (1 inch mercury) Note: If there is any variance from the specifications in the tables above, refer to the procedure below.Introduction
Use the following procedures to test the fuel system pressure systems of the engine.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 lineThe following procedure is used to measure the fuel pressure after the secondary filter. Check the output pressure of the fuel transfer pump. Inspect the return pressure regulating valve to the fuel tank and to measure the vacuum at the primary filter.Required Tools
Illustration 1 g06495102
Tooling (T1) 198-4240 Digital Pressure Indicator Gp
(T1a) 198-4234 Digital Indicator
(T1b) 198-4237 Pressure Sensor Gp
(T1c) 198-4238 Pressure Sensor Gp
(T1d) 198-4239 Pressure Sensor Gp
(T1e) 251-9600 Pressure Sensor Gp
(T1f) 198-4236 Adapter Cable As
Table 4
Required Tools
Item Quantity Part Number Part Name
T1 1 1U-5470
or
198-4240 Engine Pressure Group
or
Digital Pressure Indicator
T1a 1 198-4234 Digital Indicator
T1b 1 198-4237 Pressure Sensor Gp
(0 to 3,445 kPa (0 to 500 psi))
T1c 1 198-4238(1) Pressure Sensor Gp
(0 to 34,450 kPa (0 to 5,000 psi))
T1d 1 198-4239 Pressure Sensor Gp
(0 to 41,368 kPa (0 to 6,000 psi))
T1e 1 251-9600(2) Pressure Sensor Gp
(0 to 68,900 kPa (0 to 10,000 psi))
T1f 1 198-4236 Adapter Cable As
(1) This sensor must be purchased separately, it is not included in the 198-4240 Digital Pressure Indicator Gp
(2) This sensor can only be used on large diameter pressure taps like 6V-3965 Fitting.