5031530 JOHNSON STOPPER, UPPER THRUST

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 lineFuel Pressure Readings
Different configurations are used for the low-pressure side of the fuel system. The different configurations cause different fuel pressure readings.Lower Fuel Pressure Configuration
The typical fuel pressure of the engine at operating temperature can vary. With new fuel filters, the fuel pressure at the secondary fuel filter base must be within the following ranges. At cranking speed (100-135 rpm), the fuel pressure can be 75 kPa (11 psi). At low idle (700 to 900 rpm), the fuel pressure can be 450 50 kPa (65 7 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 500 50 kPa (73 7 psi).The performance of the unit injector deteriorates when the fuel pressure drops below 390 kPa (57 psi). Low-power complaints and erratic operation can occur in this situation. Check for a plugged fuel filter or air in the fuel lines as possible causes for these complaints before replacing fuel system components.Higher Fuel Pressure Configuration
The typical fuel pressure of the engine at operating temperature can vary. With new fuel filters, the fuel pressure at the secondary fuel filter base must be within the following ranges. At cranking speed (100-135 rpm), the fuel pressure can be 75 kPa (11 psi). At low idle (700 to 900 rpm), the fuel pressure can be 650 50 kPa (94 7 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 705 50 kPa (102 7 psi).The performance of the unit injector deteriorates when the fuel pressure drops below 390 kPa (57 psi). Low-power complaints and erratic operation can occur in this situation. Check for a plugged fuel filter or air in the fuel lines as possible causes for these complaints before replacing fuel system components.There are two available pressure regulator valves and there are two sets of pressures:
Equipped with 327-0376 Check Valve Gp. At cranking speed (100–135 rpm), The fuel pressure can be 500 kPa (72 psi). At low idle (700 to 900 rpm), the fuel pressure can be 500 to 700 kPa (72 to 101 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 600 to 900 kPa (87 to 131 psi).
Equipped with 228-7381 Check Valve Gp. At cranking speed (100–135 rpm), The fuel pressure can be 350 kPa (51 psi). At low idle (700 to 900 rpm), the fuel pressure can be 450 to 650 kPa (65 to 94 psi). At high idle (1800 to 2000 rpm), the fuel pressure can be 600 to 800 kPa (87 to 116 psi).Checking 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 g00294866
1U-5470 Engine Pressure Group
Illustration 2 g01124671
Location of fuel pressure tap
(1) Plug
Illustration 3 g02124374
(2) Pressure tapTo check the fuel transfer pump pressure, remove the plug (1) from the fuel filter base. Install the pressure gauge and appropriate fittings from the 1U-5470 Engine Pressure Group and start the engine.Check the fuel pressure of the engine with the 1U-5470 Engine Pressure Group. The engine pressure group includes Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group". This instruction provides information about the usage of the group.