FUEL PUMP UNIT CONSTRUCTION/OPERATION[L3]
id0114a2101500
Fuel Pump Unit
• The fuel pump unit mainly consists of a pressure regulator, fuel pump, fuel reserve cup, and fuel filter (low-pressure).
• A pressure regulator is built-in due to the adoption of a returnless fuel system.
• A hard-plastic fuel pump unit, with an integrated pressure regulator and fuel pump, has been adopted to simplify the fuel line.
• The fuel pump unit cannot be disassembled.
• Fuel in the fuel reserve cup is suctioned out through the fuel filter (low-pressure) by the fuel pump, and pumped to the fuel filter (high-pressure). Pressure regulated return fuel is sent back to the fuel reserve cup or the fuel tank through the pressure regulator.
• If return fuel pressure exceeds the given value, the relief valve discharges return fuel into the fuel pump unit without passing it through the venturi. Due to this, return fuel pressure is maintained below the given value.
Pressure Regulator
• The pressure regulator is mainly consists of a spring, release valve, and diaphragm.
• Built into the fuel pump unit due to adoption of a returnless fuel system.
• Cannot be removed because it is integrated with the fuel pump unit.
• Pressure regulates fuel discharged by the fuel pump to approx. 390 kPa {3.98 kgf/cm2, 56.6 psi} using the spring, diaphragm, and release valve, and then pumps it to the fuel distributor.
• If fuel pressure exceeds approx. 390 kPa {3.98 kgf/cm2, 56.6 psi} the release valve opens to discharge unnecessary fuel pressure (fuel).