Yamaha FJR1300R Service Manual

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Contents

1 - 8GENINFOFEATURESPressure regulatorIt regulates the fuel pressure that is applied to the injectors that are provided in the cylinders in orderto maintain a constant pressure difference with the pressure in the intake manifold.The fuel that is delivered by the fuel pump fills the fuel chamber through the fuel inlet of the regulatorand exerts pressure on the diaphragm in the direction for opening the valve.A spring that is provided in the spring chamber exerts pressure on the diaphragm in the direction forclosing the valve, in contrast to the pressure of the fuel. Thus, the valve cannot open unless the fuelpressure overcomes the spring force.An intake vacuum is applied to the spring chamber via a pipe. When the pressure of the fuelexceeds the sum of the intake vacuum and the spring force, the valve that is integrated with the dia-phragm opens, allowing the fuel to return from the fuel outlet to the fuel tank, via the fuel returnhose.As a result, because the intake vacuum fluctuates in accordance with the changes in the operatingconditions in contrast to the constant volume of fuel supplied by the pump, the valve opening/clos-ing pressure also changes to regulate the return fuel volume. Thus, the difference between the fuelpressure and the intake manifold pressure remains constant at a prescribed pressure.1 Spring chamber2 Spring3 Diaphragm4 Fuel inlet5 Fuel outlet6 Fuel chamber7 Valve8 Intake manifold vac-uum pressureÈ Spring pressureÉ Fuel pressureÊ Vacuum pressureÈÉÊ1 2346785