1973 OPEL GT-R fuel cap

FUEL SYSTEMSC- 37
must always be removed before the distributor can be
removed.
EVAPORATION CONTROL SYSTEM1. The function of the fuel evaporation control sys-
tem is to absorb the fuel vapors developing in the fuel
tank, especially when vehicle is parked, due to at-
mospheric pressure and temperature influences, and
to release these fuel vapors during vehicle operation.
2. This system utilizes the property of the activated
carbon to absorb and expel fuel vapors. The activated
carbon container is installed on the left front side of
the engine compartment. The fuel tank has a
non-vented tiller cap. Vent hoses are joined in the area of
the tank. A plastic evaporation line leads from there
along vehicle underbody to the activated carbon con-
tainer.
3. A small tube above the throttle valve body con-
nects the carburetor to the activated carbon con-
tainer. In this way, the fuel vapor collected in the
activated carbon container is fed through the carbu-
retor into the combustion chambers during engine
operation.
4. The carburetor is provided with an internal and
outside ventilation, the activated carbon container is
also connected to the outside ventilation (only effec-
tive when engine is idling). In this way, the fuel
vapors escaping to the outside during engine idle are
collected by the activated carbon container and fed
into the combustion chambers.
5. The vent lines are connected to the upper part of
the activated carbon container. Fresh air enters
through a foam rubber filter at the lower part andflows, together with the fuel vapor, to the carburetor.
Metered bores in the hose fittings of the fuel tank
control the air
- and fuel vapor flow through the
activated carbon container to the carburetor, and the
pressure release in the fuel tank and ensure complete
purging of the carbon container.
Care must be taken not to mix up lines at the ac-
tivated carbon container. See Figure
6C-2.6. The metered bores in the fuel tank fitting and an
overflow protection in the fuel tank, which prevents
a complete filling of the tank, prevents fuel flows into
the activated carbon container rendering it useless.
FUEL FILTERAn AC fuel filter type (GF 423) is being used on all
1973 Opels. A vapor return line returns vapors in the
fuel line back to the fuel tank. Proper installation of
the filter is essential. The vapor return line connector
must be on top (highest point) for proper operation.
See Figure
6C-3.1. LINE TO
CARBURETOR2. FILTER
3. LINE FROM
4. VAPOR
RETURN LINE
6C-3Figure
6C-3 Fuel Filter
MAINTENANCE AND ADJUSTMENTSFigure
6C-2 Carbon CanisterCLEANING FUEL PUMP STRAINER

6C- 381973 OPEL SERVICE MANUALCAUTION:Because the fuel pump is below fuel tank
level, fuel
will drain from the tank. when the supply
hne is disconnected from the fuel pump.1. Pull fuel supply line and rubber connector from
fuel pump. Plug rubber connector to prevent fuel
loss.2. Remove fuel pump cap, gasket and plastic
strainer.
3. Cover center opening in sediment bowl with finger
and blow out sediment bowl with compressed air.
4. Wash plastic strainer in solvent; if strainer does
not clean-up or is damaged, replace strainer.
5. Install clean parts, noting the following:
(a) Strainer must be properly seated with projections
facing upward.(b) A new cap gasket must be positioned over
strainer.
(c) Sealing ring must be in place on cap retaining
screw.6. Reconnect fuel supply line. Start engine and check
for leaks.
EVAPORATION CONTROL SYSTEMProper performance of the system requires the use of
a non-vented fuel tank cap, hose connections be leak-
free, and all hoses routed correctly to avoid a
pinched or blocked line.
Maintenance requirements demand only that the ac-
cumulator purge air tilter, an oiled foam filter assem-
bled in the bottom of the canister, be replaced at
12,CKO mile intervals. Under extremely dusty condi-
tions, more frequent attention may be required.
Figure
W-4 Exploded View of Opel 1900 and Manta Fuel Tank

FUEL SYSTEMSC- 39
MAJOR REPAIR
FUEL TANK OPEL 1900 AND MANTAThe fuel tank is located below the luggage compart-
ment floor panel and is attached with a strap.
The plastic tank vent hoses join in a connector from
where the fuel vapors escape through a fourth
ho%attached to the upper flange of the tank.
On all vehicles, the vent hose is connected to an
activated carbon container mounted to the front
wheel house panel.
Removal1. With a pinch clamp, close connecting hose be-
tween tank and fuel line. After loosening hose clamp,
pull hose off fuel line. See Figure
6C-5.Figure
6C-52. Take off tiller cap and unscrew tiller neck from
side panel. Pull off fuel tank hose and plug connect-
ing tubes on tank. See Figures 6C-4 and
6C-6.3. With a jack and suitable support (wooden board
12
x 12”), support fuel tank and unscrew strap.
Lower fuel tank. See Figure
6C-7.
Installation1. Raise tank into position and install strap.
2. Install 4 filler neck to side panel attaching screws
and filler cap.Figure
K-6Figure
6C-73. Install tank vent hoses and fuel line, taking care
not to kink lines.
4. Remove pinch clamp from fuel line.
FUEL TANK (GT MODELS)
Removal1. Disconnect battery.
2. Remove rubber cap, unscrew fuel line from tank,
and drain fuel. See Figure
6C-8.3. Remove spare tire and jack.
4. Remove spare tire hold-down and brackets. See
Figure
6C-9.5. Remove spare tire support panel.

FUEL SYSTEM6C- 41
covered with sound deadening compound. See Fig-
ure
6C-10.7. Remove fuel tank vent hose and tiller hose. See
Figure 6C- 11.
8. Remove fuel tank attaching bolts and gauge wire
and remove tank.
Installation
1. Install tank and tighten attaching bolts.
2. Replace gauge wire. Install vent hose, making cer-
tain it is not kinked and seal vent hose hole in floor.
3. Install spare tire support attaching brackets, sup-
port panel, hold-down, and brackets.
4. Install spare tire and jack.
5. Install fuel line and rubber cap.
6. Connect battery.FUEL LINES. FUEL GAUGE TANK UNITS
All fuel lines are plastic and have an outside diameter
of
,240 inches. Unlike metal lines, plastic lines are
not flared.
When replacing a plastic line, place the line in hot
water to make it flexible. Using the old line as a
pattern, form the new line. Let the line cool com-
pletely, then route it in the same location as the old
line. To prevent chafing against the underbody, nine
(9) rubber grommets are placed at points on the line
between the fuel tank and the fuel pump. When re-
placing fuel gauge tank units, coat gasket on both
sides and first threads of attaching screws with seal-
ing compound.
CLEANING FUEL TANK
1. Remove fuel tank.
2. Empty fuel tank through filler neck.
3. Remove fuel gauge tank unit, together with suc-
tion tube and screen. Clean screen and blow out from
cover side. Flush fuel tank.
SPECIFICATIONSFuel Tank Capacity (Gallons)
Opel 1900 and Manta
....................................................................................................11.9GT
....................................................................................................................................13.2FuelGaugeType
........................................................................................................Electrical
Fuel Pump Type
......................................................................................................Mechanical
Fuel Pump Drive
..................................................................................Eccentric on Camshaft
Fuel Pump Pressure at 1950 (RPM)................................................................3.1 to 3.7 P.S.I.FuelFilter
............................................................................................................In-LineFilter

6E- 581973 OPEL SERVICE MANUAL
Figure 6E-34 Leaf Spring Installed
1 6E-36
Figure 6E-36 Checking Vent Valve Adjustment
39. Check compression of vent valve lower spring. It
should be compressed
l/4 inch with throttle valve
completely closed. See Figure
6E-36.40. Correct by bending valve lever.
Figure
6E-35 Installing Cover Gasket
SPECIFICATIONS
GENERAL SPECIFICATIONSCompression Ratio
........................................................................................................7.6 to 1
Fuel Required
................................(...........................................................................Low Lead
Fuel Tank Capacity (Gallons)
Opel1900andManta..
....................................................................................................11.9
GT...................................................................................................................................13.2Fuel Gauge Type
........................................................................................................Electrical
FuelPumpType
......................................................................................................Mechanical
FuelPumpDrive
..................................................................................EccentriconCamshaft
Fuel Pump Pressure at 1950 RPM
......................................................................3.1 to 3.7 psi
FuelFilter
............................................................................................................In-LineFilter
CarburetorMakeandType................................................I-Solex2BBLAutomaticChoke
AirCleanerElementType
..........................................................................FiberMesh-Paper

6F- 601973 OPEL SERVICE MANUAL
EMISSION CONTROL SYSTEMS
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
DescriptionandOperationofO.E.C.S.. . . . . . . . . . . . . . . . . . . . . . . .Exhaust
GasRecirculationSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Testing Therm0 Air Cleaner Operation
. . . . . . . . . . . . . . . . . . . . . .Exhaust
GasRecirculationSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Exhaust GAS Recirculation System
. . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Removal and Replacement of O.E.C.S. Units
. . . . . . . . . .SPECIFICATIONS:
Opel Emission Control System Specifications
. . . . . . . .Page No.
6F-60
6F-62
6F-62
6F-636F-636F-636F-64
DESCRIPTION AND OPERATION
OPEL EMISSION CONTROL SYSTEM (O.E.C.S.)All 1973 cars must be capable of passing certain tests
which measure the quantity of unburned impurities
in the exhaust system. Federal law places a limit on
the hydrocarbon and carbon monoxide emissions
from the exhaust system. The purpose of this law is
to keep the atmosphere cleaner, particularly in popu-
lous areas where these impurities add to the smog
problem. Basically, excessive exhaust emissions are
caused by incomplete combustion of the air-fuel mix-
ture in the cylinders.
The basic components of the OECS on the 1.9 liter
engines are (1) leaned out carburetion, (2) heated air
(except GT), and (3) tuned spark timing.
(1) The carburetor idle system is leaned out and
special features are incorporated into the carburetors
to make possible additional idle mixture adjustments
over and above those manufactured into the carbu-
retors.
(2) The heated air package consists of a heat stove,
a corrugated paper heated air pipe, and an air cleanercontaining a temperature controlled door operated
by vacuum through a temperature sensor. See Figure6F-1.The heat stove is a sheet metal cover, shaped to and
bolted onto the exhaust manifold. Air drawn in along
Figure
6F-1 Heated Air System Installed