Fuel Filter; Idle Valve - Volvo 240 1989 Service Manual

Safety scre8n
When the throNle valve switch is closed during idling,
the control unit receives a signal, enabling it to send
current to the air valve electric motor to keep the idle
rpm at the correct level.
Des;gn and funct;ol].
Fuel sys tem LH2.4 - 240
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Fuel filter
The luel filter is adjaoentto the fuel pump and both are
mounted on a plate below the veh icle under the back
seat.
Itconsists of a paper filter and asafety screen to catch
any pieces of the paper filter which come loose .
Idle valve
, I n order to set the correct air valve opening and thus
achieve constant idte speed , the control unit uses in­
formation from the air mass meter regarding the
amount of air entering the engine and from the
ignition system control unit regarding rpm. This
means that the idle valve is not affected by air leaks
or a jammed throttle valve.
When the current is off, a spnng sets the idle valve
opening for an idle speed between 1.000 and 1,100
rpm .
Once the engine is running, the control uni t ensures
that the idle valve is more or less open al all rotation
speeds in order to prevent the development of unnec­
essarily high negative pressure in the intake manifofd
when the throttle shutter closes suddenly during
deceleration.
The control unit receives a signal from the AC control
when the AC is tumed on or off to enable it to adjust
the idle valve. Signals are also sent to the control unit
from the AC compressor so that the idle valve can be
adjusted each time the compressor turns on or off .
..
There is no signal to the control unit when the shuNer
switch is open. When driving , the control unit keeps
the idle valve partially open so that the negalive
pressure in the intake manifold is reduced when the
gas pedal is released .
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