Yamaha XV1700P Service Manual page 26

Pressure regulator
It regulates the fuel pressure that is applied to the injectors that supply fuel to the cylinders in order
to maintain a constant pressure.
The fuel that is delivered by the fuel pump fills the fuel chamber through the fuel inlet of the regulator
and 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 for
closing the valve, in contrast to the pressure of the fuel. Thus, the valve cannot open unless the fuel
pressure overcomes the spring force.
By the atmospheric pressure applied to the spring chamber and when the fuel pressure exceeds the
sum of the atmospheric pressure and spring force, the diaphragm opens the valve, allowing fuel to
return to the fuel tank from the return hose.
Therefore, the fuel pressure applied to the injectors by the pressure regulator is controlled by the
atmospheric pressure and the spring force to maintain the fuel pressure in accordance to the
changes of the atmospheric pressure.
1 Spring chamber
2 Spring
3 Diaphragm
8
5
4 Fuel inlet
5 Fuel outlet
6 Fuel chamber
1 - 9
FEATURES
È
É
1
7
6
7 Valve
8 Atmospheric pressure
sensor
GEN
INFO
2
3
4
È Spring pressure
É Fuel pressure