Exhaust Gas Recirculation (Egr) System Function Checks; Crankcase Breathing; Evaporative Loss Control System - Triumph TR7 Owner's Manual

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Function Checks
Warm the engine to normal runnmg temperature. Ensure that
the Idle speed returns to normal Blip the throttle and observe
the valve. which should open and close as the engine speed
changes.
If the valve is nOI operatmg. remove the E.G.
A.
valve and
check the valve operation usmg a vacuum test gauge. Fit a
new
EG R
valve if
It 1$
found to be defective.
Crankcase Breathing
To ensure that piston 'blow
by'
gases do not escape from the
crankcase to the atmosphere, a depression
1$
maintained
In
the crankcase under all operatmg conditions. This IS achIeved
by connecting the crankcase breathing hOUSing 10 a POIi'll
between the air meter flap and the throttle plate ie. a
constant depression region,
On Rover 3500 and TRS models air is drawn into the right
hand rock.er cover via an air filter and restnctor and drawn off
from the engine on the left hand rock.er cover. A flame trap is
fitted
In
the draw off housing.
Evaporative Loss Control System
The function of this control system IS to prevent fuel
hydrocarbon vapours from entenng the atmosphere. This IS
achllwed by providing no external fuel tank. breathing system
and as an alternative venting the tank through two adsorption
canisters located In the engine compartment.
To prevent the canisters flooding due to thermal expanSion of
any fuel in the tank. the tank filler neck IS entered well down
Into the tank, and a pipe let into the tank at maximum fuel
level vents into the filler neck to allow for fuel expansion. A
liqUid vapour separator IS Incorporated into the fuel tank vent
Pipe to reduce the quantity of vapour passed to the canisters.
Any fuel vapour IS purged from the canisters once the engine
IS running by means of a connection to a constant depreSSion
region between the air meter flaps and the throttle butterfly.
WARNING: The use of compressed air to clean an
adsorption canister or clear a blockage in the evaporative
system is very dangerous. An explosive gas present in a
partly saturated canister may be ignited by the heat
generated when compressed air passes through the
canister.
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