Technical data

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MA/N,

COiMPQNENTS

FUEL PUMP

The pump is of the rotating type with

cells

Sand

rollers, driven by an electric

moto;

which remains immersed in the

fuel

under pressure downstream the

pumping

,unit.

This arrangement re-

sults~in

reduction

in noise and fur-

thermore

the fuel under pressure acts

as ~

hydraulic support between the

spi’ndle

Iand

relative supporting

bu-

shesl

The

‘pump

delivers more

fuel

than the engine effectively requires, in

orde?

to maintain effective pressure in

the supply system under all’ possible

operating conditions, If the key is

in-

serted

in the ignition and turner to the

“MAPCIA” (running) position, the

pump

is not supplied with power;

when

the key is turned on the “AVVIA-

MENTO”

(starting) position, the

cqn-

trol unit’measures the r.p.m. from igni-

‘tio,n

,distributor and, when this

ex-

ceed~s

,determined

value sail control

unit seessto supplying the fuel pump.

Whit’

this electrical safety circuit, in

the case of a faulty electroinjector

,wifh~

ingition inserted,

one

prevents

the corrisponding circuit

‘from

being

filied

with ‘fuel.

Fu:el

p,ump

DAM~ER

Thei

damper is

connected

upstream

the fuei distribution tube. The function

of the

‘damper

is to eupress

hamme-

rings

‘that

cari

occur especially when

the

:engine

is running on

low

r.p.m..

The~

hammering is generated by jumps

fuel!

pressure that arise from the

opening and closing of the electroin-

jectors or the pressure regulator.

d’2

790088330 1

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-

cally in parallel and

/nject

simulta-

neous!y

once for

each

rotation

bof

the

crankshaft half of the necessary

quan-

tity of fuel.

04-5

An ete,ctroinjector

consists

essentiaffy

of a

coil, a moving tore, a guide for the

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

resultiof

magnetic

field created by the

magnet and this is effected when the

electronic CU sends an appropriate

electric signal.

The stroke of the moving tore, and

theretore of the needle, is

very

limited

(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

part.

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

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.

SUePLEMENTAtiY

,AIR

SOLENO,ID

VALVE

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

affected

by the temperature of the cy

lindei head in

such

a’way

as to obtain

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.

October 1988