ELECTRIC PETROL PUMP
The petrol pump is of the multi roller-vane type, driven by an electric motor which is energized as long as the
ignition is switched on. The rotor, which is fitted eccentrically in the pump housing, has metal roller vanes in
grooves around t.he periphery which, when they are forced outwards under the action of the centrifugal force, ensure
the system-is sealed.
Fuel is drawn into the cavities which,appear in between the roller-vanes, and is then forced into the injection
piping.
The electric motor is submerged’ in fuel. However, there .is no fire risk, since there is never any combustible
mixture in the pump housing. The pump supplies more fuel than the engine consumes under full load, so that
there is always sufficient pressure in the fuel system, whatever the engine speed. Excess fuel flows back to
the tank.
Once the ignition is on, the pump operates at the same time as the starter motor. Once the engine is running, the
airflow sensor energizes the pump.
Thanks to this type of.system, if an injector is faulty ( leaks ) the cylinder in question cannot be flooded if one
has ommitted to switch the ignition off.
PETROL FILTER (1) :
A fuel filter, fitted between the pump and the injectors, prevents any impurities from reaching the injectors.
PETROL PRESSURE REGULATOR ( 2 ) :
The fuel pressure is maintained constant by the pressure regulator. It comprises a metal housing
is a diaphragm., One side of the dipphragm.is subjected to the fuel under pressure, and the other 2
to the action of a calibrated spring.
inside which
side is subjected
When the fuel pressure is in excess of 2 bars ( 29 psi ), the diaphragm lifts and allows fuel to flow back to the
tank.
The pressure provided by the regulator is pre-adjusted at the factory. The chamber on the side of the spring is
connected via a flexible pipe to the inlet manifold. Therefore, the difference between the pressure in the inlet
manifold and that of the fuel is maintained constant.
For any engine load, the drop in pressure at the injectors is therefore the same.
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