Pontiac Fiero 1988 Service Manual page 546

DRIVEABILITY
AMD
EMISSIONS -
FUEL
INJECTION
(TBI)
6E2-C3-1
SECTIOISI O
E V A P O R A T I V E E M I S S I O N C O N T R O L S Y S T E M (EI
C O N T E N T S
GENERAL DESCRIPTION . . . C3-1
PURPOSE C3-1
E V A P O R A T I V E EMISSION S Y S T E M C3-1
RESULTS O F I N C O R R E C T O P E R A T I O N . . . . . C3-1
DIAGNOSIS . C 3 - 2
V I S U A L C H E C K O F CANISTER C 3 - 2
F U N C T I O N A L TESTS
Canister Purge? Valve
O N - C A R S E R V I C E ,
F U E L V A P O R C A N I S T E R ,
P A R T S I N F O R M A T I O N
. C3-2
.• C3-2
. . C3-2
. C 3 - 2
GENERAL DESCRIPTION
PURPOSE
The basic evaporative emission control system
(EECS) used on all vehicles is the charcoal canister
storage method. This method transfers fuel vapor from
the fuel tank to an activated carbon (charcoal) storage
device (canister) to hold the vapors when the vehicle is
not operating. When the
engine
is running, the fuel
vapor is purged from the carbon element by intake air
flow and consumed in the normal combustion process.
EVAPORATIVE EMISSION SYSTEM
This system uses a canister with an integral
diaphragm operated purge valve. The fuel vapors
vent from the fuel tank to the canister. When the
engine is running, manifold vacuum is supplied to the
top tube of the purge valve (Control Vacuum Signal)
which lifts the valve diaphragm and opens the valve.
The lower tube on the purge valve (PCV Tube) is
connected to a timed port above the TBI throttle valve.
The rate of purge is controlled through this port by
throttle location.
To increase the capacity of the fuel tank there is a
vapor storage tank located near the fuel tank. Vapors
vent to the canister from this storage tank.
RESULTS OF INCORRECT OPERATION
Evidence of fuel loss or fuel vapor odor can be
caused by:
Liquid fuel leaking from fuel lines or TBI
Inoperative purge valve
Disconnected, misrouted, kinked,deteriorated
or damaged vapor hoses, or control hoses
Air cleaner or air cleaner
gasket
improperly
seated.
PCV
CONTROL VACUUM
FUEL TANK
PURGE VALVE
5-28-85
* 6 S 2808-6E
F i g u r e C3-1 - V a p o r C a n i s t e r
Poor idle, stalling and poor driveability can be
caused by:
Inoperative purge valve
Damaged canister
Hoses split, cracked and or, not connected to
the proper tubes.