1973 OPEL GT-R fuel pressure

6A- 121973 OPEL SERVICE MANUALINTAKE AND EXHAUST MANIFOLD REMOVAL
AND
INSTALLATION
Removal1. Disconnect battery.
2. Remove air cleaner.
3. Disconnect throttle linkage at carburetor.
4. Disconnect vacuum advance line at carburetor.
5. Remove fuel line at carburetor inlet.
6. Remove positive crankcase ventilation hose at
rocker arm cover.
7. Disconnect E.G.R. lines from carburetor and in-
take manifold.
8. Disconnect exhaust pipe.
9. Remove six bolts attaching manifold assembly to
cylinder head and remove manifold and carburetor
as an assembly. Discard manifold gasket.
To separate intake and exhaust, manifold, remove
carburetor and four bolts using Tool J-23016, attach-
ing intake manifold to exhaust manifold. Always in-
stall a new manifold intermediate gasket when the
manifolds are separated.
Installation1. Install new manifold gasket and place manifold in
position.
2. Install manifold bolts. New manifold to cylinder
head gasket must be installed whenever a manifold
is removed.
3. When installing the manifold, start with the No.
1 and No. 2 bolts. See Figure 6A-16. Gradually
tighten both bolts until snug. Then continue with the
rest of the bolts in the sequence illustrated in Figure6A-16. Torque bolts to 33 lb. ft.
Figure 6A-16 Manifold
Bolt Tightening Sequence4. Connect parts removed in Steps 1 thru 8 above.
CYLINDER HEAD REMOVAL AND INSTALLATION
Removal1. Drain coolant from radiator and block. Loosen
drain plug on right side of engine to avoid coolant
entering into cylmder bores. Drain plug is located onthe right rear of cylinder block above oil pressure
switch.2. Remove hoses from thermostat housing. Collect
coolant as it contains anti-freeze.
3. Remove 6 intake and exhaust manifold attaching
bolts and swing assembly aside.
4. Remove spark plug wires from plugs.
5. Remove bracket bolt holding spark plug wires
away from cylinder head.
6. Remove rocker arm cover.
7. Remove 10 cylinder head bolts using 12 MM ser-
rated drive J-22915, and 2 cylinder head to timing
chain cover bolts with a 6MM hex head wrench. See
Figure 6A- 17.
Figure 6A-17 Serrated Bits
8. Remove three bolts attaching plate to front of
cylinder head.
9. Remove plastic screw from end of camshaft.
10. Remove 3 bolts attaching camshaft sprocket to
cylinder head. Slide sprocket off of camshaft and
remove head. Place head on bench supported at each
end by a block of wood to prevent damage to valves.
Installation1. Install in reverse procedure to removal, paying
particular attention to the following:

6C- 361973 OPEL SERVICE MANUAL
FUEL SYSTEM
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Fuel Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .Evaporation Control System
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
(Not Applicable)
MAINTENANCE AND ADJUSTMENTS:
Cleaning Fuel Pump Strainer.,....................................
*.Evaporation Control System
. . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Fuel Tank
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel Lines and Fuel Tank Gauge Units
. . . . . . . . . . . . . . . . . . . . . .SPECIFICATIONS:
Fuel System Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.6C-366C-376C-376C-386C-396C-416C-41
DESCRIPTION AND OPERATION
FUEL PUMPThe 1.9 liter engine uses a push rod type fuel pump.
The push rod is actuated by an eccentric on the
distributor shaft. The push rod is held in contact
with the eccentric at all times by a push rod spring.
Each time the push rod is on the high part of the
eccentric, the lighter diaphragm spring will push the
diaphragm to replace any fuel used in the carburetor.
The diaphragm seldom operates through a full
stroke; under normal driving conditions, the dia-
phragm moves only a few tenths of an inch.
Fuel pump pressure is determined by the compres-
sion of the diaphragm spring. Low pressure or pres-
sure leak- down generally indicates a leaky
diaphragm or check valves.
Two holes in the lower part of the fuel pump serve
to ventilate the space below the diaphragm and to
drain any fuel which may have entered. If any fuel
comes from these holes, this indicates a defective
diaphragm.When replacing the fuel pump, make sure the asbe-
stos spacer is in place with a gasket on each side. See
Figure 6C- 1. Because of the location of the fuel pump
eccentric on the distributor shaft, the fuel pump
Figure
6C-1 Installing Push Rod Type Fuel Pump

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

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.461973OPELSERVICEMANUAL
Sectional View Of Carburetor
1Carburetor cover
2Vent valve
3 Ball valve (pressure valve)
4Injection tube
5Primary venturi
6Choke valve
7Vent
iet8 Air correction
iet9Enrichment
10 Float needle valve
11 Float needle valve seal ring12 Fuel line connecting tube
13 Carburetor cover gasket
14Leaf spring
15Float
&amber16 Pressure reduction valve17Pump lever
18Diaphragm
19 D iophragm spring
20 Ball valve (suction valve)
21Float
22 Pump connecting rod
23Metering
iet24Emulsion tube
25 Bore without function
26Throttle valve
27Intermediate lever
28Main venturl
29 Vacuum passage for automatic choke
30 Throttle valve body
31Gasket
32 Vent valve lever
Figure 6E-2 Sectional View of Carburetor

6~. 46,1973 OPEL SERVICE MANUAL
ary barrel, it is provided with g transfer system.
When the secondary throttle valve starts to open,
two‘ports (which are normally just above the closed
valve) are uncovered, causing fuel to feed into the
secondary bore just before the secondary nozzle
starts feeding. This provides for an additional enrich-
ment of the air-fuel mixture at the beginning of full
throttle operation. See Figure
6E-7.
nInFlFigure
6E-7 Primary to Secondary Transfer System
Full Thrdttle Enrichment SystemIf the secondary throttle valve is fully opened, the
vacuum in the throttle valve area is reduced so that
the transfer ports (mentioned above) stop feeding.
However, the vacuum increases greatly in the sec-
ondary venturi area. An enrichment tube which pro-
trudes into the primary venturi area, feeds fuel
continuously during full throttle operation. See Fig-
ure
6E-2.
Acceleration SystemWhenever the throttle is closing, the suction stroke
of the diaphragm pump causes fuel to flow from the
float chamber through the inlet ball valve into the
pump chamber. When the throttle valve is opened
the diaphragm is moved inward by the pump con-
necting rod and the pump lever. Fuel is injected into
the primary bore through the injector tube. The
amount of fuel is determined by the pump stroke.
The inlet ball valve in the pump chamber prevents
fuel from flowing back into the float chamber during
the pressure stroke of the pump. The outlet ball valve
prevents air from being drawn into the injector tube
during the suction stroke of the pump. See Figure6E- 8.
Float Bowl VentilationWhile driving, the float bowl is ventilated from insideFigure
6E-8 Acceleration System
the carburetor. That is, the float bowl is connected
through the vent valve with the area under the air
cleaner.
When the engine is idling or off, the ventilation from
inside is cut off and ventilation from the charcoal
canister is cut in. The upper spring now seats the
valve on the upper seat. See Figure
6E-9.
-6E-9
Figure
6E-9 Float Bowl VentilationThe advantage of an inside vent while driving is that
air cleaner restriction does not enrichen the air fuel
mixture. The purpose of the charcoal canister vent
while idling or after shutting-off a hot engine, is to
prevent excess fuel vapors from entering the intakemanifold and outside air. Excess fuel vapors may
cause an idling engine to stall, or may make it dif-
ficult to restart a hot engine.

CARBURETOR AND THROTTLE LINKAGE6E- 49DIAGNOSIS
CARBURETORCondition I
Hesitation or Stall Upon Light AccelerationCorrection
1. Check spark plugs and plug gap. Plug gap should
be
,030 in.
2. Check dwell and timing.
3. Adjust carburetor.
4. Accelerator pump should discharge fuel between
throttle plate and venturi wall with engine off. If aim
is not correct, use needlenose pliers to slightly bend
nozzle so proper aim is achieved. See Figure 6E- 10.
CORRECT ACCELERATOR
PUMP DISCHARGE
NOZZLE AIM
\Figure 6E-10 Pump Shot Aim
Road test car. If hesitation still exists, check for the
folI0 wing:1. Plugged accelerator pump discharge nozzle.2. Dirt in accelerator pump circuit.
3. Defective inlet check ball.
4. Defective accelerator pump pressure relief valve.
5. Defective accelerator pump diaphragm.
6. Maladjusted accelerator pump linkage.
Condition II
Hard Start Afier Hot Soak
CorrectionPerform Steps l-4 in Condition I.
Condition Ill
Hard Start When Engine Is Cold
Correction1. Align groove on choke cover with pointer on
choke housing. See Figure
6E-17.2. Set fast idle.
3. Replace distributor points if pitted.
4. Check spark plugs and gap at
,030.5. Set dwell and timing.
If above procedure does not correct problem, replace
with new automatic choke assembly.
Condition IV
Rough, Erratic, or No Idle
Correction1. Check spark plugs and gap at
,030.2. Check dwell angle and ignition timing.
3. Clean idle jet and passages with air hose. See Fig-
ure
6E-5.4. Check manifold to head bolt torque. Should be 33
lb.ft.5. Check automatic choke linkage alignment.
6. Adjust carburetor.

6E- 561973 OPEL SERVICE MANUAL
valve stop screw. Loosen the stop screw until the
valve is completely closed. Turn the screw in l/4turn from closed position, hold, and tighten lock nut.
This is done to insure that the throttle blade will not
stick closed. See Figure
6E-30.PUMPFigure 6E-30 Adjusting Secondary Throttle Valve Gap
24. Install accelerator pump connecting rod in lower
hole of primary throttle shaft lever and cotter pin in
outboard hole at accelerator pump actuating lever
end. Paying attention to proper arrangement of cot-
ter pin and washers. See Figure
6E-2.25. With throttle plate completely closed, there
should be no clearance between the pump levei and
the pump plunger rod.
26. If a clearance is present, loosen 4 accelerator
Figure
6E-31 Accelerator Pump CoverFigure 6C32 Accelerator Pump Cover
pump cover retaining screws and allow the
dia-’phragm spring to push plunger against lever so that
a zero clearance exists. Then retighten the screws.
See Figures
6E-3 1 and 6E-32.27. Insert accelerator pump discharge nozzle so that
the bent tube end points into suction channel of the
primary barrel.
28. Fill the bowl with fuel.
29. With fuel in bowl, slowly open the throttle and
observe the accelerator pump pressure relief valve
exhaust ports and where it seats into the bowl. See
Figure
6E-33. Fuel should not be bleeding back into
the bowl from the exhaust ports or where the relief
valve seats, but a steady stream of fuel should dis-
charge from the discharge nozzle.
30. With fuel in bowl, rapidly open the throttle atid
observe the exhaust ports of the pressure relief valve.
See Figure
6E-33. Fuel should~exhaust’from the ac-
celerator pump pressure relief valve exhaust ports.
3 1. If the pressure relief valve malfunctions, remove
it and replace with a new one.
32. No float adjustment is possible, so check position
of float arm by comparing with a new float of thesame carburetor type. If float arm is bent, replace
float.