Fiat Bravo Service Manual page 248

Engine
Fuel system
10.
FUEL MANIFOLD
The fuel manifold, which has the function of distributing the fuel to the injectors, is made from die-cast
aluminium and incorporates the housings for the injectors and for the pressure regulator.
The fuel inlet is achieved with a sealed fixing bolt.
The fuel recirculation is obtained by means of a pipe inside the manifold connected at one end to the
regulator and at the other end to the outer fuel return pipe to the tank.
FUEL PRESSURE REGULATOR
This is a differential diaphragm device, adjusted during manufacture to a pressure of 3.00 ± 0.05 bar.
The fuel under pressure, coming from the pump, exerts a force on the flow valve (7) opposed by the cali-
brated spring (8). When the calibration pressure is exceeded, the flow valve opens and the excess fuel
returns to the tank, thereby stabilizing the pressure in the circuit.
In addition, via the pick up (9), the vacuum in the inlet manifold (at which the nose of the injector) also
finds itself, acts on the regulator diaphragm, reducing the load exerted by the calibration spring.
In this way the differential in pressure between the fuel and the environment (inlet manifold) in which
the injector finds itself in all engine operating conditions is kept constant.
Consequently, the injector flow rate (for a certain supply voltage) depends only on the injection time
established by the control unit.
NOTE The pressure is assumed by the control unit as a fixed parameter: as a result the regulator should
never be tampered with so as not to alter the mixture strength for the engine.
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Bravo-Brava
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2
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P4A38BJ01
Print no. 506.670