848655 Volvo.Penta Tube

High 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 ".
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.
Note: Place pressure gauges in-line with fuel lines when taking readings. Do not plug the outlet port of a fuel system component to take pressure readings.
Use the following procedure in order to measure the fuel pressure that is 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 achieves an average reading and a steady needle. Keep the gauge above the measuring point.
Illustration 2 g01133865
(1) Test port (2) Air purge (3) Pressure regulating valve (4) Bypass valve for the Fuel filter
Install the 1U-5470 Engine Pressure Group into port (1) . This port is the proper test port.
Adjust the engine speed to 1800 rpm with no load.
The fuel pressure should be 586 kPa (85 psi) nominal. Record the pressure.
If excessive pressure is found, check the conditions that are listed previously under the "High Fuel Pressure" heading.
Illustration 3 g01133866
Standard secondary fuel filter base (5) Fuel line from head (6) Fuel line to head (7) Fuel line from transfer pump
Use the following procedure to check the output of the fuel transfer pump:
Remove return fuel line (5) .
Install the 1U-5470 Engine Pressure Group into the port that contained the return fuel line fitting.
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.
Illustration 4 g01133870
Fuel transfer pump (side view) (8) Access plug
If the pressure is less than 655 kPa (95 psi), the fuel transfer pump is weak. The pressure regulating valve in the pump may be stuck or worn. The pressure regulating valve is located under access plug (8) . Remove the access plug. 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, replace the fuel transfer pump. If dirt is found, clean the valve assembly and reinstall the valve assembly. Reinstall access plug (8) .
Check the fuel pressure again. Replace the fuel transfer pump if the fuel pressure still measures less than 655 kPa (95 psi). The fuel transfer pump is operating properly if the fuel pressure measures at least 690 kPa (100 psi) to 724 kPa (105 psi).
Once the fuel transfer pump has been confirmed as properly operating, check the fuel pressure again at the secondary fuel filter base. Refer to Step 2. If the fuel pressure is not at the nominal specification, continue to Step 3.
Use the following procedure to inspect the return fuel pressure regulating valve:
Return fuel pressure regulating valve (3) is located on the bottom of the fuel filter base.
Inspect return fuel pressure regulating valve (3) for wear.
C