Fiat 1996 Brava Service Manual page 387

Engine
Fuel system
Bravo-Brava ty
TD100
10.
®
j w a ^
Flow rate supplement
In order to facilitate both starting up the en­
gine and the supply of full power, a system is
fitted which, by altering the stroke of the
pumping element pistons, allows an increase
in the maximum fuel flow rate.
The three following operating modes are of
special interest:
1) Operation during starting
Whilst the engine is being started up, the in­
take transfer pressure (1) is relatively low
which allows the spring (2) to overcome the
force exerted by the pistons (5) and extend in
such a way as to move the sliding plates (3)
outwards.
Under these circumstances the pistons (4)
are in contact with the shorter side of the
plates (3) with a consequent increase of the
stroke and therefore also the value of the
maximum flow rate.
2) Operation with turbocharger not operat­
ing
During normal operation, the intake transfer
pressure (1) is greater than the opposing
force exerted by the spring (2) and this al­
lows the pistons (5) to move the sliding
plates (3) inwards.
In this way the pistons (4) are in contact with
the longer side of the plates (3) with a conse­
quent decrease in the stroke and conse­
quently the value of the maximum flow rate.
3) Operation with turbocharger working
The operation of the turbocharger causes an
intake pressure (6) at the control valve (7)
which causes the movement of an internal
piston which places the transfer pressure in­
let duct (8) in contact with the return ducts
(9 and 10).
The decrease in pressure at the piston (5), al­
lows the spring (2) to overcome the pressure
of the inlet fuel (1).
The extending of the spring (2) causes the
movement of the plates (3) with a conse­
quent increase of the piston (4) stroke and
the value of the fuel flow rate..
8
IX-96 - Cancels and replaces
Print no. 506.670/08