Fiat Bravo Service Manual page 133

Bravo-Brava l@i
12v
Engine
Fuel system
10.
A positive injector supply current is supplied through the fuel pump relay; the circuit is earthed in the
control unit via terminal 2 1 .
Fuel pressure regulator
The mechanical diaphragm regulator (1) is
fitted in the injector turret (2).
The function of the fuel pressure regulator is
to maintain fuel feed pressure to the injector
at a level of about 1 bar.
Fuel under pressure from the electric pump
reaches hydraulic chamber (3) of the pres­
sure regulator.
If pressure on membrane (4) exceeds a level
of 1 bar, it overcomes the load on counter-
spring (5), and moves plate (6) to allow f u ­
el to flow out through a channel (7) in the
tank.
Hole (9) in the top chamber (8) of the regu­
lator brings chamber 8 into communication
with the outside so that a vacuum does not
build up inside the chamber.
When the engine stops, fuel feed is also
shut off. The pump check valve and injector
close. In this way, feed pressure is main­
tained for a certain period in the hydraulic
section.
This form of operation prevents the formation of vapour bubbles as a result of fuel in the system being
heated by the engine to ensure trouble-free starting at all times.
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