Evaporative Control System (Evap); Reservoir (Carbon Filter); Evap Valve; System Relay, Fuses - Volvo 240 1989 Service Manual

Design and function
Fuel system L H2.4 - 240
Ignition system
contol unil
FUIII
system
co ntrol unit
SYl tem relay
iQ:::='J
~Stl,-===
~~/
fJ
I )
Carbon
. fihM
System relay
Governed by the control unit , it provides current to
the fuel pump, the injectors, the cold start valve, the
air mass meter and to certain control unit functions .
The system relay and its functions are protected by a
20 amp fuse.
Fuses
The system relay is protected by a 25 amp fuse and
the tank pump by a 15 amp fuse .
Evaporative Control System (EVAP)
This system handles the gases that result Irom nor­
mal fuel lank evaporation, keeping Ihem from escap­
ing and pollu1ing the air.
Via a hose system , the luel vapor passes from the
filler opening through a roll-over valve to a reservoir
("canister', "carbon IIfter-). The fuel vapor is
absorbed here. n 1e reservoir is provided with an
EVAP valve which prevents leakage of fuel vapor
while the en gine is not in operaH on.
®
Reservoir (carbon IIIter)
The fu el vapors from the fue l tank enter the top of the
active carbon filter and are absorbed. Air is pushed
out through a channel in the bottom of the filter.
Depending on temperature and other conditions , the
filter can bind approx . 90 grams of fuel.
®
Roll-over valve
If
the vehicle leans sideways at more than a 45'
angle, this valve closes , helping to prevent fuel spills
during accidents.
@)
EV AP val ve
This valve is located at the top of the carbon filter and
is closed when the engine is turned off. It's also
closed during idling in order not to interfere with the
automatic idle settings or make the fuel mi xture too
rich. The valve is closed using vacuum pressure
taken Irom the intake manifold and through being
connected to the throttle shutter positive terminal.
Increased engine load opens the EVAP valve , allow ­
ing fuel vapor to flow from the carbon filter into the
engine intake manifold . Air is drawn in at the same
time through the bottom channel. Under normal
conditions , the filter is emptied of fu el in 15 to 20
minutes .
16