Nissan Stanza/200SX/240SX 1982-1992 Repair Guide

Carburetor

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The carburetor used is a 2-barrel down-draft type with a low speed (primary) side and a high speed (secondary) side.

All models have an electrically operated anti-dieseling solenoid. As the ignition switch is turned off, the valve is energized and shuts off the supply of fuel to the idle circuit of the carburetor.

ADJUSTMENTS



Throttle Linkage Adjustment
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Open the automatic choke valve by hand, while turning the throttle valve by pulling the throttle lever, then set the choke valve in the open position.
  6.  

If equipped with a vacuum controlled throttle positioner, use a vacuum hand pump to retract the throttle positioner rod.

  1. Adjust the throttle cable at the carburetor bracket, so that a 1.02.0mm of free pedal play exists.
  2.  

Dashpot Adjustment

See Figure 1

A dashpot is used on carburetors with automatic transaxles and some manual transaxles. The dashpot slowly closes the throttle on automatic transmissions to prevent stalling and serves as an emission control device on all late model vehicles.

The dashpot should be adjusted to contact the throttle lever on deceleration at approximately 1,4001,600 rpm of engine operation.



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Fig. Fig. 1: Dashpot adjustment

Before attempting to adjust the dashpot, make sure the idle speed, timing and mixture adjustments are correct.

  1. Loosen the lock-nut (turn the dashpot, if necessary) and make sure the engine speed drops smoothly from 2,000 rpm to 1,000 rpm in 3 seconds.
  2.  
  3. If the dashpot has been removed from the carburetor, it must be adjusted when installed. Adjust the gap between the primary throttle valve and the inner carburetor wall, when the dashpot stem comes in contact with the throttle arm. The dashpot gap is 0.660.86mm (manual transaxle) or 0.490.69mm (automatic transaxle).
  4.  

Secondary Throttle Linkage Adjustment

See Figure 2

All carburetors discussed in this guide are two stage type carburetors. On this type of carburetor, the engine runs on the primary barrel most of the time, with the secondary barrel being used for acceleration purposes. When the throttle valve on the primary side opens to an angle of approximately 50° (from its fully closed position), the secondary throttle valve is pulled open by the connecting linkage. The 50° angle of throttle valve opening works out to a clearance measurement of 7.48.4mm (Stanza) between the throttle valve and the carburetor body. The easiest way to measure this is to use a drill bit. Drill bits from sizes H to P (standard letter size drill bits) should fit. If an adjustment is necessary, bend the connecting link between the two linkage assemblies.



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Fig. Fig. 2: Secondary throttle linkage adjustment

Float Level Adjustment

See Figure 3

The fuel level is normal if it is within the lines on the window glass of the float chamber (or the sight glass) when the vehicle is resting on level ground and the engine is off.

If the fuel level is outside the lines, remove the float housing cover. Have an absorbent cloth under the cover to catch the fuel from the fuel bowl. Adjust the float level by bending the needle seat on the float.



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Fig. Fig. 3: Float level adjustment

The needle valve should have an effective stroke of about 1.5mm. When necessary, the needle valve stroke can be adjusted by bending the float stopper.

Be careful not to bend the needle valve rod when installing the float and baffle plate, if removed.

Fast Idle Adjustment

See Figure 4

On the Stanza models, the fast idle cam lever is located next to the fast idle cam screw, so the choke cover does not have to be removed. On the 1985 Stanza, disconnect the Fast Idle Breaker harness at the carburetor.

  1. Remove the carburetor from the vehicle. Refer to the necessary service procedures in this section.
  2.  


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!

  1. Remove the choke cover, then place the fast idle arm on the 2nd step of the fast idle cam. Using the correct wire gauge, measure the clearance A between the throttle valve and the wall of the throttle valve chamber (at the center of the throttle valve). It should be 0.660.80mm (MT) or 0.810.95mm (AT).
  2.  

The first step of the fast idle adjustment procedure is not absolutely necessary.

  1. Install the carburetor on the engine.
  2.  



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Fig. Fig. 4: Adjusting the fast idle cam-Stanza

  1. Start the engine, warm it to operating temperatures and check the fast idle rpm. The cam should be at the 2nd step. Engine speed should be 2,400-2,700 rpm (MT) or 2,800-3,100 rpm (AT).
  2.  
  3. To adjust the fast idle speed, turn the fast idle adjusting screw counterclockwise to increase the fast idle speed and clockwise to decrease the fast idle speed.
  4.  

Fast Idle Breaker Adjustment
1985-86 STANZA

See Figure 5

  1. Start the engine and warm it to operating temperatures without racing it.
  2.  
  3. Check the engine speed and the breaker operation, it should be high revolution at the start, then idle speed when warm.
  4.  
  5. Disconnect the fast idle breaker harness connector at the carburetor. Using an ohmmeter, check the fast idle breaker for continuity; place one lead on the breaker's ground wire and the other lead on the No. 8 pin of the harness connector.
  6.  



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Fig. Fig. 5: Checking the continuity of the fast idle breaker-Stanza 1985 and later models

Checking is performed when the breaker is cold (less than 68°F) and the choke plate closed.

  1. If there is no continuity, replace the breaker.
  2.  
  3. If an ohmmeter is not available, check the breaker with the engine running (harness connector installed), if the breaker does not warm up, replace it.
  4.  

Cam Follow Lever Adjustment
STANZA

See Figure 6

Hold the choke plate closed, turn the adjusting screw until there is no clearance between the cam follow lever and the fast idle cam.



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Fig. Fig. 6: Adjusting the cam follow lever-Stanza

Automatic Choke Adjustment
  1. With the engine cold, make sure the choke is fully closed (press the accelerator pedal all the way to the floor and release).
  2.  
  3. Check the choke linkage for binding. The choke plate should be easily opened and closed with your finger. If the choke sticks or binds, it can usually be freed with a liberal application of a carburetor cleaner made for the purpose. A couple of quick squirts normally does the trick; if not, the carburetor will have to be disassembled for repairs.
  4.  
  5. The choke is correctly adjusted when the index mark on the choke housing (notch) aligns with the center mark on the carburetor body. If the setting is incorrect, loosen the three screws clamping the choke body in place and rotate the choke cover left or right until the marks align. Tighten the screws carefully to avoid cracking the housing.
  6.  

Choke Unloader Adjustment

The choke assembly must be cold for this adjustment.

  1. Close the choke valve completely.
  2.  
  3. Hold the choke valve closed by stretching a rubber band between the choke piston lever and a stationary part of the carburetor.
  4.  
  5. Open the throttle lever fully.
  6.  

On the Stanza, the unloader adjusting lever is connected to the primary throttle plate shaft, an intermediate cam is connected to the choke lever by a choke rod.

  1. Adjustment is made by bending the unloader tongue. Gauge the gap between the choke plate and the carburetor body to 2.05-2.85mm.
  2.  

Vacuum Break Adjustment

See Figure 7

  1. With the engine cold, close the choke completely.
  2.  
  3. Pull the vacuum break stem straight up as far as it will go.
  4.  
  5. Check the clearance between the choke plate and the carburetor wall. Clearance should be 3.123.72mm above 68°F; 1.652.25mm below 41°F.
  6.  
  7. On the Stanza models, adjustment is made by bending the tang at the choke plate lever assembly.
  8.  

Remove the choke cover, then connect a rubber band to the choke lever to hold it shut.



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Fig. Fig. 7: Vacuum break adjustment

Accelerator Pump Adjustment

If a smooth constant stream of fuel is not injected into the carburetor bore when the throttle is opened, the accelerator pump needs adjustment.

The Stanza accelerator pump is of a different design and is not adjustable; if it is not operating correctly, replace it.

Anti-Dieseling Solenoid

Check this valve if the engine continues to run after the key has been turned off.

  1. Run the engine at idle speed and disconnect the lead wire at the anti-dieseling solenoid. The engine should stop.
  2.  
  3. If the engine does not stop, check the harness for current at the solenoid. If current is present, replace the solenoid. Installation torque for the solenoid is 1325 ft. lbs. for CA20 engines.
  4.  

REMOVAL & INSTALLATION



  1. Remove the air cleaner.
  2.  
  3. Disconnect and mark the electrical connector(s), the fuel and the vacuum hoses from the carburetor.
  4.  
  5. Remove the throttle lever.
  6.  
  7. Remove the four nuts and washers retaining the carburetor to the manifold.
  8.  
  9. Lift the carburetor from the manifold. Do not tilt the carburetor over when removed from the manifold.
  10.  

To install:
  1. Remove and discard the gasket used between the carburetor and the manifold. Clean all vacuum passages on intake manifold if necessary.
  2.  
  3. Install carburetor on the manifold, use a new base gasket and torque the carburetor mounting nuts EVENLY to 913 ft. lbs.
  4.  
  5. Install the throttle lever.
  6.  
  7. Connect the electrical connector(s), the fuel and the vacuum hoses to the carburetor. Replace the fuel line gas clamps as necessary.
  8.  
  9. Install the air cleaner.
  10.  
  11. Start engine, warm engine and adjust as necessary.
  12.  

OVERHAUL



See Figures 8, 9 and 10

Efficient carburetion depends greatly on careful cleaning and inspection during overhaul, since dirt, gum, water and/or varnish in or on the carburetor parts are often responsible for poor performance.

Overhaul your carburetor in a clean, dust free area. Carefully disassemble the carburetor, referring often to the exploded views. Keep all similar and look-alike parts segregated during disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

When the carburetor is disassembled, wash all the parts (except diaphragms, electric choke units, pump plunger and any other plastic, leather, fiber or rubber parts) in clean carburetor solvent. Do not leave parts in the solvent any longer than is necessary to sufficiently loosen the deposits. Excessive cleaning may remove the special finish from the float bowl and choke valve bodies, leaving these parts unfit for service. Rinse all parts in clean solvent and blow them dry with compressed air to allow them to air dry. Wipe clean all cork, plastic, leather and fiber parts with a clean, lint-free cloth.



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Fig. Fig. 8: Exploded view carburetor assembly-CA20 engine



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Fig. Fig. 9: Exploded view carburetor assembly-CA20 engine



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Fig. Fig. 10: Exploded view carburetor assembly-CA20 engine

Blow out all passages and jets with compressed air, be sure that there are no restrictions or blockages. Never use wire or similar tools for cleaning purposes; clean the jets and valves separately, to avoid accidental interchange.

Check all the parts for wear or damage. If wear or damage is found, replace the defective parts. Especially check the following:

  1. Check the float needle and seat for wear. If wear is found, replace the complete assembly.
  2.  
  3. Check the float hinge pin for wear and the float(s) for dents or distortion. Replace the float if fuel has leaked into it.
  4.  
  5. Check the throttle and choke shaft bores for wear or an out-of-round condition. Damage or wear to the throttle arm, shaft or shaft bore will often require replacement of the throttle body. These parts require a close tolerance of fit; wear may allow air leakage, which could affect starting and idling.
  6.  

Throttle shafts and bushings are not included in overhaul kits. They can be purchased separately.

  1. Inspect the idle mixture adjusting needles for burrs or grooves. Any such condition requires replacement of the needle, since you will not be able to obtain a satisfactory idle.
  2.  
  3. Test the accelerator pump check valves. They should pass air one way but not the other. Test for proper seating by blowing and sucking on the valve. Replace the valve if necessary. If the valve is satisfactory, wash the valve again to remove breath moisture.
  4.  
  5. Check the bowl cover for warped surfaces with a straightedge.
  6.  
  7. Closely inspect the valves and seats for wear and/or damage, replacing as necessary.
  8.  
  9. After the carburetor is assembled, check the choke valve for freedom of operation.
  10.  

Carburetor overhaul kits are recommended for each overhaul. These kits contain all gaskets and new parts to replace those that deteriorate most rapidly. Failure to replace all parts supplied with the kit (especially gaskets) can result in poor performance later.

Some carburetor manufacturers supply overhaul kits of three basic types: minor repair, major repair and gasket kits. Basically, they contain the following:

Minor Repair Kits:


All gaskets
 
Float needle valve
 
Volume control screw
 
All diaphragms
 
Spring for the pump diaphragm Major Repair Kits:
 
All jets and gaskets
 
All diaphragms
 
Float needle valve
 
Volume control screw
 
Pump ball valve
 
Main jet carrier
 
Float
 

After cleaning and checking all components, reassemble the carburetor, using new parts and referring to the exploded view. When reassembling, make sure that all screws and jets are tight in their seats but do not overtighten as the tips will be distorted. Tighten all screws gradually in rotation. Do not tighten needle valves into their seats; uneven jetting will result. Always use new gaskets. Be sure to adjust the float level when reassembling.

 
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