Main Components; Fuel Pump; Fuel Pressure Regulator; Electro Injectors - Alfa Romeo 33 Workshop Manual

FUEL PUMP

The pump is of the rotating type with
as ~ a~ hydraulic support between the
than the engine effectively requires, in
the supply system under all' possible
operating conditions, If the key is in-
trol unit'measures the r.p.m. from igni-
unit seessto supplying the fuel pump.
the case of a faulty electroinjector
the corrisponding circuit 'from being
the fuei distribution tube. The function
of the 'damper is to eupress hamme-
the :engine is running on low r.p.m..
in fuel! pressure that arise from the
opening and closing of the electroin-
jectors or the pressure regulator.
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FUEL PRESSURE REGULATOF)
The fuel under pressure enters the lo-
wer chamber of the regulator and acts
on a membraneiwhich, overcomin~g the
action of a spring, rises togheter with
a small plate and openslthe passage
to tank return t,ube. In addition to the
regulating function of the spring,
'which has a fixed setting, there is also
that of the vacuum pressure of the
supply manifold transmitted to the're-
'gulator Upper chamber via a hose con-
nected to the manifold.
When this pressure from the supply
manifold increases the membrane ri-
ses, opening the fuel return passage
and determining an equal decrease in
the fuel pressure itself. Thepurpose of
this additional adjustment is'to main-
tain the jumps in pressure"between
the fuel upstream the electroinjectors
and the air in,the manifold constant. In
this way the fuel delivered depends'ex-
clusively on the opening time of the
electroinjector itself. .
1 Hammering
2 Pressure regulator
3 Vacuum,
tube
ELECTROINJECTORS
There is one electromagnetically ac-
tuated injecter for each cylinder; the
electroinjectors are connectedelectri-
crankshaft half of the necessary quan-
tity of fuel.
An ete,ctroinjector consists essentiaffy
of a
needle and the needle. The tore of the
moving magnet is in one piece with
the needle which is pressed against
the sealed seating of the body of the
electroinjector by a spring. the needle
of the electroinjector 'is opened as a
magnet and this is effected when the
electronic CU sends an appropriate
electric signal.
The stroke of the moving tore, and
(0.15 mm approx.) as a consequence
of a stop disc which has the purpose
of preventing the moving tore from
banging against the fixed interna1
p a r t .
The opening 'tirne of the 'needle is 2-10
ms according to the 'signal arriving
from the CU. The tip of the electroin-
jector is fitted with a thermal insula-
ting bushing in teflon, the purpose of
which is to prevent the evaporation of
the fuel and the consequent crystali-
sation of the dry deposit on the nee-
dle. This bushing #,must not therefore
be'removed when fitting the electroin-
jector.
The iupplementary air solenoid valve
determines, with the engine cold, the
passage of supplementary air to the
engine by means of the accelerator
throtfle by-pass.
A bi-metallic lamina inside the'valve is
maximum closing of the'by-pass when
the engine is hot. In addition to this, a
heater winding heats the lamina and
closes the by-pass more quickly than
would occur with the heating of the
whole engine mass.
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