GM Camaro 1982-1992 Repair Guide

Carburetors

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The V6 engine is equipped with the Rochester E2SE carburetor, V8 engines use the E4ME and E4MC. These carburetors are of the downdraft design and are used in conjunction with the CCC system for fuel control. They have special design features for optimum air/fuel mixture control during all ranges of engine operation.

An electric solenoid in the carburetor controls the air/fuel ratio. The solenoid is connected to an Electronic Control Module (ECM) which is an on-board computer. The ECM provides a controlling signal to the solenoid. The solenoid controls the metering rod(s) and an idle air bleed valve, thereby closely controlling the air/fuel ratio throughout the operating range of the engine.

MODEL IDENTIFICATION



General Motors Rochester carburetors are identified by their model code. The first number indicates the number of barrels, while one of the last letters indicates the type of choke used. These are V for the manifold mounted choke coil, C for the choke coil mounted in the carburetor body, and E for electric choke, also mounted on the carburetor. Model codes ending in A indicate an altitude-compensating carburetor.

Because of their intricate nature and computer controls, the E2SE, E4ME and E4MC carburetors should only be serviced by a qualified technician.

PRELIMINARY CHECKS



The following should be observed before attempting any adjustments.

  1. Thoroughly warm the engine. If the engine is cold, be sure that it reaches operating temperature.
  2.  
  3. Check the torque of all carburetor mounting nuts and assembly screws. Also check the intake manifold-to-cylinder head bolts. If air is leaking at any of these points, any attempts at adjustment will inevitably lead to frustration.
  4.  
  5. Check the manifold heat control valve (if used) to be sure that it is free.
  6.  
  7. Check and adjust the choke as necessary.
  8.  
  9. Adjust the idle speed and mixture. If the mixture screws are capped, don't adjust them unless all other causes of rough idle have been eliminated. If any adjustments are performed that might possibly change the idle speed or mixture, adjust the idle and mixture again when you are finished.
  10.  

Before you make any carburetor adjustments make sure that the engine is in tune. Many problems which are thought to be carburetor related can be traced to an engine which is simply out-of-tune. Any trouble in these areas will have symptoms like those of carburetor problems.

ADJUSTMENTS



Fast Idle
ROCHESTER E2SE
  1. Refer to the emission label and prepare the vehicle for adjustment.
  2.  
  3. Place the fast idle screw on the highest step of the fast idle cam.
  4.  
  5. Turn the fast idle screw to obtain the fast idle speed.
  6.  

ROCHESTER E4ME AND E4MC

The fast idle adjustment must be performed according to the directions of the emissions label.

Float and Fuel Level

See Figures 1 and 2

ROCHESTER E2SE
  1. Remove the air horn and gasket.
  2.  
  3. While holding the retainer in place, push the float down lightly against the needle.
  4.  
  5. Place a measuring gauge on the float at the farthest point from the float hinge.
  6.  
  7. To adjust, remove the float and bend the arm up or down. Also check the float alignment.
  8.  
  9. Install the air horn and gasket.
  10.  



Click image to see an enlarged view

Fig. Fig. 1: Float adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Remove the air horn and gasket from the float bowl. Hold the float retainer down firmly. Push the float down (lightly) against the needle.
  2.  
  3. Position a T-scale over the toe of the float 1 / 16 in. (1.6mm) from the end of the float toe.
  4.  
  5. If the float level varies more than 1 / 16 in. (1.6mm) from the specified setting, it must be reset.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: E4ME/E4MC float level adjustment

FLOAT LEVEL TOO HIGH
  1. Hold the float retainer in place.
  2.  
  3. Push down on the center of the float until the correct level is obtained.
  4.  

FLOAT LEVEL TOO LOW
  1. Lift out the metering rods and remove the solenoid connector screws.
  2.  
  3. Turn the lean mixture solenoid screw clockwise, counting and recording the number of turns required to seat the screw in the float bowl.
  4.  
  5. Turn the screw counterclockwise and remove it. Lift the solenoid and the connector from the float bowl.
  6.  
  7. Remove the float and bend the arm up to adjust. The float must be correctly aligned after adjustment.
  8.  
  9. To install the components, reverse the order of removal. Back out the solenoid mixture screw the number of turns that was recorded earlier.
  10.  

Throttle Linkage
ROCHESTER E2SE

No adjustment of the throttle cable can be made.

ROCHESTER E4ME AND E4MC

Due to the design of the throttle cable, no adjustments of the throttle linkage can be made.

Choke Unloader (Primary)

See Figures 3 and 4

ROCHESTER E2SE
  1. Connect a rubber band to the intermediate choke lever and open the throttle to allow the choke valve to close.
  2.  
  3. Set up the angle gauge and set the gauge to specifications.
  4.  
  5. Using a vacuum source, retract the vacuum break plunger. Make sure that the air valve rod does not interfere with the retraction of the vacuum break plunger.
  6.  
  7. Support the vacuum break rod and make the adjustment by bending the rod.
  8.  



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Fig. Fig. 3: Primary vacuum break adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Connect a rubber band to the green tang of the intermediate choke shaft.
  2.  
  3. Open the throttle to allow the choke valve to close.
  4.  
  5. Set up the angle gauge and set to specifications.
  6.  
  7. Using a vacuum source, retract the vacuum break plunger. The air valve rod must not restrict the breaker plunger from fully retracting.
  8.  
  9. With the vacuum applied, turn the adjusting screw until the centering bubble of the angle gauge is level.
  10.  



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Fig. Fig. 4: Primary vacuum break adjustment on E4ME/E4MC carburetors

Choke Unloader (Secondary)

See Figures 5 and 6

ROCHESTER E2SE
  1. Connect a rubber band to the intermediate choke lever and open the throttle to allow the choke to close.
  2.  
  3. Set up the angle gauge and set the angle to specifications.
  4.  
  5. Using a vacuum source, retract the vacuum break plunger and retain the vacuum pressure.
  6.  
  7. Refer to the accompanying illustration to perform this procedure. Center the angle gauge bubble by turning an 1 / 8 in. (3mm) Allen wrench or bending vacuum break rod.
  8.  



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Fig. Fig. 5: Secondary vacuum break adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Connect a rubber band to the green tang of the intermediate choke shaft.
  2.  
  3. Open the throttle to allow the choke valve to close.
  4.  
  5. Set up the angle gauge and set the angle to specification.
  6.  
  7. Using a vacuum source, retract the vacuum break plunger.
  8.  

The air valve rod must not restrict the vacuum break plunger from fully retracting.

  1. With the vacuum applied, turn the adjusting screw or bend the vacuum break rod until the bubble of the angle gauge is centered.
  2.  



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Fig. Fig. 6: Secondary vacuum break adjustment on E4ME/E4MC carburetors

Air Valve Spring Adjustment

See Figures 7 and 9

ROCHESTER E2SE
  1. If necessary, remove the intermediate choke rod to gain access to the lock screw.
  2.  
  3. Loosen the lock screw and turn the tension adjusting screw clockwise until the air valve opens slightly.
  4.  
  5. Turn the adjusting screw counterclockwise until the air valve just closes; continue turning the screw counterclockwise according to specifications.
  6.  
  7. Tighten the lock screw. Apply lithium grease to the spring and pin.
  8.  



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Fig. Fig. 7: Air valve spring adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Loosen the lock screw and turn the tension adjusting screw counterclockwise until the air valve partly opens.
  2.  
  3. Turn the tension adjusting screw clockwise until the air valve just closes, then turn the screw clockwise a specified number of turns.
  4.  
  5. Tighten the lock screw and apply lithium grease to the spring contact area.
  6.  



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Fig. Fig. 8: Air valve spring adjustment on E4ME/E4MC carburetors

Air Valve Rod Adjustment

See Figures 9, 10 and 11

ROCHESTER E2SE
  1. Set up the angle gauge on the air valve and set the angle to specification.
  2.  
  3. Use a vacuum source to seat the vacuum break plunger.
  4.  
  5. By applying light pressure to the air valve lever, rotate it in the opening direction.
  6.  
  7. Support the air valve rod and bend it to make the adjustment.
  8.  



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Fig. Fig. 9: Air valve rod adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Using a vacuum source, seat the vacuum break plunger. The air valve must be closed.
  2.  
  3. Insert a 0.025 in. (0.635mm) plug gauge between the rod and the end of the slot.
  4.  
  5. To adjust, bend the air valve rod.
  6.  



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Fig. Fig. 10: Front air valve rod adjustment on E4ME/E4MC carburetors



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Fig. Fig. 11: Rear air valve rod adjustment on E4ME/E4MC carburetors

Choke Lever Adjustment

See Figures 12 and 13

ROCHESTER E2SE
  1. If the choke cover is riveted, drill out the rivets and remove the choke cover with the spring assembly.
  2.  
  3. Place the fast idle screw on the high step of the fast idle cam. Push the intermediate choke lever until the choke valve is closed.
  4.  
  5. Place a 0.085 in. (2.16mm) plug gauge in the choke housing hole and move the choke lever to touch the plug gauge.
  6.  
  7. Support the intermediate choke rod and bend it to make adjustment.
  8.  
  9. To install choke cover, use pop rivets.
  10.  



Click image to see an enlarged view

Fig. Fig. 12: Choke lever adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. If the choke cover plate is riveted, drill out the rivets and remove the plate assembly.
  2.  
  3. Place the fast idle cam follower on the high step of the fast idle cam.
  4.  
  5. Lift up on the choke lever to close the choke valve and insert a 0.120 in. (3mm) plug gauge into the choke housing hole. The choke lever should just touch the gauge.
  6.  
  7. To adjust, bend the choke rod.
  8.  
  9. To replace the cover plate, rivet in place.
  10.  



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Fig. Fig. 13: Choke lever adjustment on E4ME/E4MC carburetors

Choke Rod Fast Idle Cam Adjustment

See Figures 14, 15 and 16

ROCHESTER E2SE
  1. Attach a rubber band to the intermediate choke lever and open the throttle to allow the choke plate to close.
  2.  
  3. Set up the angle gauge and set the angle to specifications.
  4.  
  5. Place the fast idle screw on the second step of the cam, against the high step.
  6.  
  7. Move the choke shaft lever, to open the choke valve, make contact with the black closing tang.
  8.  
  9. Support the fast idle cam rod and bend the rod to make the adjustment. Adjustment is completed when the bubble of the angle gauge is level.
  10.  



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Fig. Fig. 14: Choke rod fast idle cam adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. Connect a rubber band to the green tang of the intermediate choke shaft.
  2.  
  3. Open the throttle to allow the choke valve to close.
  4.  
  5. Set up the angle gauge and set the angle to specifications.
  6.  
  7. Place the cam follower on the second step of the fast idle cam, against the rise of the first step. If the cam follower does not contact the cam, turn the fast idle screw additional turns.
  8.  
  9. To adjust, bend the tang of the fast idle cam until the gauge bubble is centered.
  10.  

The final fast idle speed adjustment must be performed according to the emission control label.



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Fig. Fig. 15: Choke valve angle gauge



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Fig. Fig. 16: Choke rod fast idle cam adjustment on E4ME/E4MC carburetors

Unloader Adjustment

See Figures 17 and 18

ROCHESTER E2SE
  1. Connect a rubber band to the intermediate choke lever and open throttle to allow the choke to close.
  2.  
  3. Set up the angle gauge and set the angle to specifications.
  4.  
  5. Hold the throttle lever in wide-open position and push on the choke lever to open the choke, making contact with the black closing tang.
  6.  
  7. To adjust, bend the tang until the bubble of the angle gauge is centered.
  8.  



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Fig. Fig. 17: Unloader adjustment on E2SE

ROCHESTER E4ME AND E4MC
  1. Connect a rubber band to the green tang of the intermediate shaft.
  2.  
  3. Open the throttle to allow the choke valve to close.
  4.  
  5. Set up the angle gauge and set the angle to specification.
  6.  
  7. Hold the secondary lockout lever away from the pin.
  8.  
  9. Hold the throttle lever in the wide-open position.
  10.  
  11. To adjust, bend the tang of the fast idle lever until the bubble of the angle gauge is centered.
  12.  



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Fig. Fig. 18: Unloader adjustment on E4ME/E4MC

Secondary Lockout Adjustment

See Figures 19 and 20

ROCHESTER E2SE
  1. Push down on the intermediate choke lever to hold the choke valve wide-open.
  2.  
  3. Open the throttle lever until the end of the secondary actuating lever is opposite the toe of the lockout lever.
  4.  
  5. Insert a 0.025 in. (0.635mm) plug gauge.
  6.  
  7. To adjust, bend the lockout lever tang into contact with the fast idle cam.
  8.  



Click image to see an enlarged view

Fig. Fig. 19: Secondary lockout adjustment on E2SE carburetors

ROCHESTER E4ME AND E4MC
  1. With the choke and the throttle valves closed, insert a 0.015 in. (0.38mm) plug gauge between the lockout lever and the pin. To establish clearance, bend the pin.
  2.  
  3. Push down on the fast idle cam and hold the choke valve wide open.
  4.  
  5. Insert a 0.015 in. (0.38mm) plug gauge sideways between the lockout lever and the pin. To adjust, file the end of the pin.
  6.  



Click image to see an enlarged view

Fig. Fig. 20: Secondary lockout adjustment on E4ME/E4MC carburetors

Mixture Control (M/C) Solenoid

See Figures 21, 22, 23 and 24

TRAVEL TEST

These procedures are performed on four barrel models only. Before checking the mixture control solenoid travel, it may be necessary to modify the float gauge J-9789-130 or equivalent (used to externally check the float level).

This should be done by filing or grinding sufficient material off the gauge to allow for insertion down the vertical D-shaped hole in the air horn casting (located next to the idle air bleed valve cover).

Check that the gauge freely enters the D-shaped vent hole and does not bind. The gauge will also be used to determine the total mixture control solenoid travel.

With the engine OFF and the air cleaner removed, measure the control solenoid travel as follows:

  1. Insert a modified float gauge J-9789-130 or equivalent down the D-shaped vent hole. Press down on the gauge and release it.
  2.  
  3. Observe that the gauge moves freely and does not bind. With the gauge released (solenoid in the up position), be sure to read it at eye level and record the mark on the gauge (in inches/millimeters) that lines up with the top of the air horn casting (upper edge).
  4.  
  5. Lightly press down on the gauge until bottomed (solenoid in the down position). Record (in inches/millimeters) the mark on the gauge that lines up with the top of the air horn casting.
  6.  
  7. Subtract the gauge up dimension from gauge dimension. Record the difference (in inches/millimeters). This difference is total solenoid travel.
  8.  
  9. If total solenoid travel is not within 3 / 32 - 5 / 32 in. (2.4-3.9mm), perform the mixture control solenoid adjustments. If the difference is within specifications, proceed to the idle air bleed valve adjustment.
  10.  

If adjustment is required, it will be necessary to remove the air horn and drive out the mixture control solenoid screw plug from the under side of the air horn.



Click image to see an enlarged view

Fig. Fig. 21: Checking the solenoid plunger travel

ADJUSTMENTS

Before making adjustment to mixture control solenoid, verify that the plunger travel is not correct.

  1. Remove air horn, mixture control solenoid plunger, air horn gasket and plastic filler block, using normal service procedures.
  2.  
  3. Check carburetor for cause of incorrect mixture:
    1. M/C solenoid bore or plunger worn or sticking
    2.  
    3. Metering rods for incorrect part number, sticking or rods or springs not installed properly
    4.  
    5. Foreign material in jets
    6.  

  4.  
  5. Remove throttle side metering rod. Install mixture control solenoid gauging tool, J-33815-1, BT-8253-A, or equivalent, over the throttle side metering jet rod guide and temporarily reinstall the solenoid plunger into the solenoid body.
  6.  
  7. Holding the solenoid plunger in the DOWN position, use tool J-28696-10, BT-7928, or equivalent, to turn lean mixture solenoid screw counterclockwise until the plunger breaks contact with the gauging tool. Turn slowly clockwise until the plunger makes contact with the gauging tool. The adjustment is correct when the solenoid plunger is contacting both the solenoid stop and the gauging tool.
  8.  

If the total difference in adjustment required less than3/4turn of the lean mixture solenoid screw, the original setting was within the manufacturer's specifications.

  1. Remove solenoid plunger and gauging tool and reinstall metering rod and plastic filler block.
  2.  
  3. Invert air horn and remove rich mixture stop screw from bottom side of air horn, using tool J-28696-4, BT-7967-A, or equivalent.
  4.  
  5. Remove lean mixture screw plug and the rich mixture stop screw plug from air horn, using a punch.
  6.  
  7. Reinstall rich mixture stop screw in air horn and bottom lightly, then back screw out 1 / 4 turn.
  8.  
  9. Reinstall air horn gasket, mixture control solenoid plunger and air horn to carburetor.
  10.  
  11. Adjust the M/C solenoid plunger travel as follows:
    1. Insert float gauge down D-shaped vent hole. Press down on gauge and release, observing that the gauge moves freely and does not bind. With gauge released, (plunger UP position), read at eye level and record the reading of the gauge mark (in inches/millimeters) that lines up with the top of air horn casting, (upper edge).
    2.  
    3. Lightly press down on gauge until bottomed, (plunger DOWN position). Read and record (in inches/millimeters) the reading of the gauge mark that lines up with top of air horn casting.
    4.  
    5. Subtract gauge UP position from the gauge DOWN position and record the difference. This difference is the total plunger travel. Insert external float gauge in vent hole and, with tool J-28696-10, BT-7928, or equivalent, adjust rich mixture stop screw to obtain 5 / 32 in. (3.9mm) total plunger travel.
    6.  

  12.  
  13. With solenoid plunger travel correctly set, install plugs (supplied in service kits) in the air horn, as follows:
    1. Install plug, hollow end down, into the access hole for the lean mixture (solenoid) screw. Use suitably sized punch to drive plug into the air horn until the top of plug is even with the lower. Plug must be installed to retain the screw setting and to prevent fuel vapor loss.
    2.  
    3. Install plug, with hollow end down, over the rich mixture stop screw access hole and drive plug into place so that the top of the plug is 3 / 16 in. (4.7mm) below the surface of the air horn casting. Plug must be installed to retain screw setting.
    4.  

  14.  
  15. To check the M/C solenoid dwell, first disconnect vacuum line to the canister purge valve and plug it. Ground diagnostic TEST terminal and run engine until it is at normal operation temperature (upper radiator hose hot) and in closed loop.
  16.  
  17. Check M/C dwell at 3000 rpm. If within 10-50 degrees, calibration is complete. If higher than 50 degrees, check the carburetor for a cause of rich condition. If below 10 degrees, look for a cause of lean engine condition such as vacuum leaks. If none are found, check for the cause of a lean carburetor.
  18.  



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Fig. Fig. 22: Installing the mixture control solenoid gauging tool



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Fig. Fig. 23: Adjusting the lean mixture solenoid screw



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Fig. Fig. 24: Adjusting the rich mixture stop screw

Idle Air Valve

See Figures 25 and 26

A cover is in place over the idle air bleed valve. Also, the access holes to the idle mixture needles are sealed with hardened plugs. This is done to seal the factory settings, during original equipment production. These items are NOT to be removed unless required for cleaning, part replacement, improper dwell readings or if the System Performance Check indicates the carburetor is the cause of the trouble.

ROCHESTER E4ME AND E4MC
  1. With engine OFF , cover the internal bowl vents and inlet to bleed valve and the carburetor air intakes with masking tape. This is done to prevent metal chips from entering.
  2.  
  3. Carefully drill rivet head of idle air bleed cover, with 0.110 in. (2.8mm) drill bit.
  4.  
  5. Remove rivet head and all pieces of rivet.
  6.  
  7. Lift cover off air bleed valve and blow out any metal shavings, or use a magnet to remove excess metal.
  8.  


CAUTION
Always wear eye protection when using compressed air.

  1. Remove masking tape.
  2.  
  3. Start engine and allow it to reach normal operating temperature.
  4.  
  5. Disconnect the vacuum hose from the canister purge valve and plug it.
  6.  
  7. While idling in D for automatic transmission or N for manual transmission, slowly turn the valve counterclockwise or clockwise, until the dwell reading varies within the 25-35 degree range, attempting to be as close to 30 degrees as possible.
  8.  

Perform this step carefully. The air bleed valve is very sensitive and should be turned in1/8turn increments only.

  1. If the dwell reading does not vary and is not within the 25-35 degree range, it will be necessary to remove the plugs and to adjust the idle mixture needles.
  2.  



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Fig. Fig. 25: Installing the idle air bleed valve gauging tool



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Fig. Fig. 26: Adjusting the idle air bleed valve

Idle Mixture

See Figures 27, 28 and 29

E2SE CARBURETORS
  1. Remove the carburetor from the engine.
  2.  
  3. Remove the plugs covering the idle mixture needles.
  4.  
  5. Turn the mixture needle in until slightly seated, then back it out 4 turns.
  6.  
  7. If the plug in the air horn covering the idle air bleed has been removed, replace the air horn. If the plug is still in place, do not remove it.
  8.  
  9. Remove the vent stack screen assembly to gain access to the lean mixture screw.
  10.  
  11. Using tool J-28696-10 or equivalent, turn the lean mixture screw in until lightly seated, then back out 2 1 / 2 turns.
  12.  
  13. Install the carburetor on the engine.
  14.  
  15. Disconnect the bowl vent line at the carburetor.
  16.  
  17. Disconnect the EGR hose and canister purge hose at the carburetor. Cap the ports on the carburetor.
  18.  
  19. Find the hose from port D of the carburetor to the temperature sensor and secondary vacuum break thermal vacuum switch. Disconnect and plug the vacuum hose going to the air cleaner.
  20.  
  21. Connect the positive lead of a dwell meter to the mixture control solenoid test lead (green connector). Connect the other lead to ground. Set the meter to the 6 cylinder position.
  22.  
  23. Run the engine on the high step of the fast idle cam until the cooling fan starts to cycle.
  24.  
  25. Run the engine at 3,000 rpm and adjust the lean mixture screw slowly. Allow the reading to stabilize, obtain an average dwell of 35 degrees. It is normal for the dwell to vary in a narrow range.
  26.  
  27. Return to idle.
  28.  
  29. Adjust the idle mixture screw to obtain an average dwell of 25 degrees. Allow time for the reading to stabilize.
  30.  
  31. Run the engine at 3,000 rpm and note the dwell reading. It should be varying with an average reading of 35 degrees. If it does not, repeat the earlier steps.
  32.  



Click image to see an enlarged view

Fig. Fig. 27: Idle mixture needle plug removal

E4ME CARBURETORS (ELECTRIC CHOKE)
  1. Using tool J-29030, BT-7610-B, or equivalent, turn both idle mixture needles clockwise until they are lightly seated, then turn each mixture needle counterclockwise 3 turns.
  2.  
  3. Reinstall carburetor on engine using a new flange mounting gasket, but do not install air cleaner and gasket at this time.
  4.  
  5. Disconnect the vacuum hose to canister purge valve and plug it. Readjust the idle air bleed valve to finalize correct dwell reading.
  6.  
  7. Connect the positive lead of a dwell meter to the mixture control solenoid test lead (green connector). Connect the other lead to ground. Set the meter to the 6 cylinder position.
  8.  
  9. Start engine and run until fully warm, then repeat the idle air bleed valve adjustment.
  10.  
  11. If unable to set dwell to 25-35 degrees and the dwell is below 25 degrees, turn both mixture needles counterclockwise an additional turn. If dwell is above 35 degrees, turn both mixture needles clockwise an additional turn. Readjust idle air bleed valve to obtain dwell limits. Repeat as needed.
  12.  
  13. After adjustments are complete, seal the idle mixture needle openings in the throttle body, using silicone sealant, RTV rubber, or equivalent. The sealer is required to discourage unnecessary adjustment of the setting and to prevent fuel vapor loss in that area. Reconnect canister vacuum hose.
  14.  
  15. On vehicles without an Idle Load Compensator (ILC), adjust curb idle speed if necessary.
  16.  
  17. Check, and if necessary, adjust fast idle speed as described on Vehicle Emission Control Information (VECI) label.
  18.  



Click image to see an enlarged view

Fig. Fig. 28: Lean mixture and idle mixture screw adjustment

E4MC CARBURETOR (HOT AIR CHOKE)
  1. Using tool J-29030-B, BT-7610-B, or equivalent, turn each idle mixture needle clockwise until lightly seated, then turn each mixture needle counterclockwise 3 turns.
  2.  
  3. Reinstall carburetor on engine, using a new flange mounting gasket, but do not install air cleaner or gasket at this time.
  4.  
  5. Disconnect vacuum hose to canister purge valve and plug it.
  6.  
  7. Connect the positive lead of a dwell meter to the mixture control solenoid test lead (green connector). Connect the other lead to ground. Set the meter to the 6 cylinder position.
  8.  
  9. Start engine and allow it to reach normal operating temperature.
  10.  
  11. While idling in D ( N for manual transmission), adjust both mixture needles equally, in 1 / 8 turn increments, until dwell reading varies within the 25-35 degree range, attempting to be as close to 30 degrees as possible.
  12.  
  13. If reading is too low, turn mixture needles counterclockwise. If reading is too high, turn mixture needles clockwise. Allow time for dwell reading to stabilize after each adjustment.
  14.  

After adjustments are complete, seal the idle mixture needle openings in the throttle body, using silicone sealant, RTV rubber, or equivalent. The sealer is required to discourage unnecessary readjustment of the setting and prevent fuel vapor loss in that area.

  1. On vehicles without a carburetor-mounted Idle Load Compensator (ILC) , adjust curb idle speed if necessary.
  2.  
  3. Check, and if necessary, adjust fast idle speed, as described on the Vehicle Emission Control Information (VECI) label.
  4.  



Click image to see an enlarged view

Fig. Fig. 29: Mixture needle and spring

Idle Load Compensator

See Figure 30

The idle load compensator is adjusted at the factory. Do not make any adjustments unless diagnosis leads to it, or curb idle speed is not to specification.

  1. Make certain ignition timing, mixture adjustment, vacuum hoses, fuel pressure and CCC system meets specifications.
  2.  
  3. Remove air cleaner and plug hose to thermal vacuum valve.
  4.  
  5. Connect a tachometer.
  6.  
  7. Disconnect and plug hose to EGR valve.
  8.  
  9. Disconnect and plug hose to canister purge port.
  10.  
  11. Disconnect and plug hose to idle load compensator.
  12.  
  13. Back out idle stop screw on carburetor 3 turns.
  14.  
  15. Turn air conditioning OFF.
  16.  
  17. Block drive wheels, set parking brake, place transmission in P , start and warm engine to normal operating temperature. Make certain choke is OPEN .
  18.  
  19. With engine RUNNING place transmission in D and idle load compensator fully extended (no vacuum applied). Using tool J-29607, or equivalent, adjust plunger to obtain 650-750 rpm. Locknut on plunger must be held with a wrench to prevent damage to guide tabs.
  20.  
  21. Measure distance from the locknut to tip of the plunger. This distance must not exceed 1 in. (25mm). If it does check for low idle condition.
  22.  
  23. Reconnect vacuum hose to idle load compensator and observe idle speed.
  24.  
  25. Idle speed should be between 425-475 rpm in D .
  26.  
  27. If idle speed is correct no further adjustment is necessary, proceed to the next step. If idle speed is still incorrect continue as follows:
  28.  

It may be necessary to remove the idle load compensator from the engine unless a hex key wrench is modified to clear obstructions.

  1. Stop engine, remove rubber cap from the center outlet tube.
  2.  
  3. Using a 0.90 in. (23mm) hex wrench, insert through open center tube to engage idle speed adjusting screw.
  4.  
  5. If idle speed was low, turn the adjusting screw counterclockwise approximately 1 turn for every 85 rpm low. If idle speed was high turn screw 1 turn for every 85 rpm high.
  6.  

  1. Disconnect and plug vacuum hose to the idle load compensator.
  2.  
  3. Using a hand pump, apply vacuum to the idle load compensator until fully retracted.
  4.  
  5. Adjust the idle stop screw on carburetor float bowl to obtain 450 rpm in D .
  6.  
  7. Place transmission in P and stop engine.
  8.  
  9. Reconnect the idle load compensator.
  10.  
  11. Reconnect all vacuum hoses.
  12.  
  13. Install air cleaner and gasket. Remove wheel blocks.
  14.  



Click image to see an enlarged view

Fig. Fig. 30: Idle load compensator components

Throttle Position Sensor (TPS)

See Figures 31 and 32

Before the throttle position sensor voltage output setting can be accurately checked or adjusted the idle rpm must be within specifications. The plug covering the TPS adjustment screw is used to provide a tamper-resistant design and retain the factory setting during vehicle operation. Do not remove the plug unless diagnosis indicates the TPS is not adjusted correctly, or it is necessary to replace the air horn assembly, float bowl, TPS, or TPS adjustment screw. This is a critical adjustment that must be performed accurately to ensure proper vehicle performance and control of exhaust emissions. Remove TPS plug if not already removed.

Adjustment is required only if voltage is above the following readings, as the ECM automatically zeros below 0.70 Volts.

  1. Using a 5 / 64 in. (2mm) drill bit, carefully drill a hole in the steel or aluminum plug. Be sure to drill only far enough to start a self tapping screw, the approximate drilling depth is 1 / 16 - 1 / 8 in. (1.6-3mm).
  2.  

Use care in drilling so as not to damage the TPS adjustment screw head.

  1. Start a long self tapping screw (No. 8 x 1 / 2 in.) into the drilled pilot hole in the plug. Turn the screw in only enough to ensure a good thread engagement in the drilled hole.
  2.  
  3. Place a suitable tool between the screw head and the air horn casting. Then pry against the screw head to remove the plug. A small slide hammer may also be used in this procedure. Be sure to discard the plug when it has been removed.
  4.  
  5. Connect a suitable digital voltmeter (J-29125 or equivalent) from the TPS connector center terminal (B) to the bottom terminal (C).
  6.  

Jumper wires for access can be made using terminals 12014836 and 12014837 or equivalent. Make jumper wires up with 16 gauge (1.0mm), 18 gauge (0.8mm) or 20 gauge (0.5mm) wire approximately 6 in. (152mm) long.

  1. With the ignition ON and the engine stopped, install the TPS adjustment screw and turn the screw with a suitable tool to obtain the specified voltage at the specified throttle position with the A/C controls in the OFF position.
    1. 2.8L - 0.30 volts at curb idle position
    2.  
    3. 5.0L - 0.40 volts at curb idle position
    4.  

  2.  
  3. After the adjustment has been made, install a new plug kit (supplied in the service kits), into the air horn. Drive the plug into place until it is flush with the raised pump lever boss on the casting. Clear trouble code memory after adjustment.
  4.  

The plug must be installed to retain the TPS adjustment screw setting. If a plug kit is not available, remove the TPS adjusting screw and apply thread sealer adhesive X-10 or equivalent to the screw threads. Now repeat the TPS adjustment procedure to obtain the correct TPS voltage.



Click image to see an enlarged view

Fig. Fig. 31: Throttle position sensor adjusting screw location on E2SE carburetors



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Fig. Fig. 32: Throttle position sensor adjusting screw location on E4ME/E4MC carburetors

REMOVAL & INSTALLATION



See Figures 33 through 43

Always replace all internal gaskets that are removed. Flooding, stumble on acceleration and other performance complaints are in many instances, caused by presence of dirt, water, or other foreign matter in carburetor. To aid in diagnosis, carburetor should be carefully removed from engine without draining fuel from bowl. Contents of fuel bowl may then be examined for contamination as carburetor is disassembled. Check the fuel filter.

Rochester E2SE
  1. Remove air cleaner and gasket.
  2.  
  3. Disconnect fuel pipe and vacuum lines.
  4.  
  5. Disconnect electrical connectors.
  6.  
  7. Disconnect accelerator linkage.
  8.  
  9. If equipped with automatic transmission, disconnect downshift cable.
  10.  
  11. If equipped with cruise control, disconnect linkage.
  12.  
  13. Remove carburetor attaching bolts.
  14.  
  15. Remove carburetor and EFE heater/insulator (if used).
  16.  
  17. Inspect EFE heater/insulator for damage. Be certain throttle body and EFE heater/insulator surfaces are clean.
  18.  

To install:
  1. Install EFE heater/insulator.
  2.  
  3. Install carburetor and tighten nuts alternately to the correct torque.
  4.  
  5. Connect downshift cable, as required.
  6.  
  7. Attach the cruise control cable, as required.
  8.  
  9. Connect accelerator linkage.
  10.  
  11. Connect electrical connections.
  12.  
  13. Connect fuel pipe sand vacuum hoses.
  14.  
  15. Check base (slow) and fast idle.
  16.  
  17. Install the air cleaner.
  18.  



Click image to see an enlarged view

Fig. Fig. 33: Remove the air cleaner for access to the carburetor



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Fig. Fig. 34: Use a back-up wrench when disconnecting fuel lines



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Fig. Fig. 35: If the retaining clip on the connector is broken off like this one, it should be replaced



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Fig. Fig. 36: The vacuum modulator line behind the carburetor must also be disconnected, if equipped



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Fig. Fig. 37: The accelerator cable retaining clip can be removed using a pair of needle nose pliers



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Fig. Fig. 38: The return spring and throttle valve cable must also be disconnected from the linkage



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Fig. Fig. 39: Removing the rear carburetor attaching bolts (note: a long extension is helpful here)



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Fig. Fig. 40: Removing the front carburetor attaching bolts



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Fig. Fig. 41: Always replace this gasket anytime the carburetor is removed



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Fig. Fig. 42: The emission hose routing sticker under the hood is helpful when installing the carburetor



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Fig. Fig. 43: The adjustment specifications on the emission control information label must always be followed

Rochester E4ME and E4MC
  1. Disconnect the battery and remove the air cleaner.
  2.  
  3. Disconnect the accelerator linkage.
  4.  
  5. Disconnect the transmission detent cable.
  6.  
  7. If equipped, remove the cruise control cable.
  8.  
  9. Tag and detach all of the necessary vacuum lines and electrical connections.
  10.  
  11. Disconnect the fuel line at the carburetor inlet.
  12.  
  13. Remove the attaching bolts and remove the carburetor.
  14.  

To install:
  1. Position the carburetor onto the manifold and install the attaching bolts.
  2.  
  3. Connect the fuel line at the carburetor inlet.
  4.  
  5. Attach all of the vacuum lines and electrical connections, as tagged during removal.
  6.  
  7. If equipped, install the cruise control.
  8.  
  9. Connect the transmission detent cable.
  10.  
  11. Connect the accelerator linkage.
  12.  
  13. Install the air cleaner and connect the battery.
  14.  

OVERHAUL



Carburetor overhaul kits are recommended for each overhaul. These kits contain all gaskets and new parts to replace those which 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 for three basic types: minor repair; major repair; and gasket kits. Certain parts may be expected in most kits based on the desired degree of overhaul.

Minor Repair Kits:


All gaskets
 
Float needle valve
 
All diaphragms
 
Spring for the pump diaphragm
 

Major Repair Kits:


All jets and gaskets
 
All diaphragms
 
Float needle valve
 
Pump ball valve
 
Float
 
Complete intermediate rod
 
Intermediate pump lever
 
Some cover hold-down screws and washers
 

Gasket kits:


All gaskets
 

Efficient carburetion depends greatly on careful cleaning and inspection during overhaul, since dirt, gum, water, 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 and directions packaged with the rebuilding kit. Keep all similar and look-alike parts separated during disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

When the carburetor is disassembled, wash all parts (except diaphragms, electric components, 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 or allow them to air dry. Wipe clean all cork, plastic, leather, and fiber parts with a clean, lint-free cloth.

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

Check all 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.
  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 or repaired by a qualified carburetor overhaul shop.

  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 check ball and spring as necessary. If the valve is satisfactory, wash the valve parts again to remove breath moisture.
  4.  
  5. Check the bowl cover for warped surfaces with a straightedge.
  6.  
  7. Closely inspect the accelerator pump plunger for wear and damage, replacing as necessary.
  8.  
  9. After the carburetor is assembled, check the choke valve for freedom of operation.
  10.  
  11. Check, repair or replace parts, if the following problems are encountered:
  12.  

Flooding


Inspect the float valve and seat for dirt, deep wear grooves, scores and improper sealing
 
Inspect the float valve pull clip for proper installation; be careful not to bend the pull clip
 
Inspect the float, the float arms and the hinge pin for distortion, binds, and burrs. Check the density of the material in the float; if heavier than normal, replace the float
 
Clean or replace the fuel inlet filter and check the valve assembly
 

Hesitation


Inspect the pump plunger for cracks, scores or cup excessive wear. A used pump cup will shrink when dry. If dried out, soak in fuel for 8 hours before testing
 
Inspect the pump duration and return springs for weakness or distortion
 
Check the pump passages and the jet(s) for dirt, improper seating of the discharge checkball or the temperature bypass disc and/or scores in the pumpwell. Check the condition of the pump discharge check ball spring, replace as necessary
 
Check the pump linkage for excessive wear; repair or replace as necessary
 

Hard Starting-Poor Cold Operation


Check the choke valve and linkage for excessive wear, binds or distortion
 
Test the vacuum break diaphragm(s) for leaks
 
Clean or replace the fuel filter
 
Inspect the float valve for sticking, dirt, etc.
 
Also check the items under "Flooding"
 

Poor Performance-Poor Gas Mileage


Clean all fuel and vacuum passages in the castings
 
Check the choke valve for freedom of movement
 
Check the Mixture Control (M/C) solenoid for sticking, binding or leaking
 
Check the air valve and secondary metering rod for binding conditions. If the air valve or metering rod is damaged or the metering rod adjustment is changed from the factory setting, the air horn assembly must be replaced. Also check the air valve lever spring for proper installation
 

Rough Idle


Inspect the gasket and gasket mating surfaces on the casting for nicks, burrs or damage to the sealing beads
 
Check the operation and sealing of the mixture control solenoid
 
Clean all of the idle field passages
 
If removed, inspect the idle mixture needle for ridges, burrs or being bent
 
Check the throttle lever and valves for binds, nicks. or other damage
 
Check all of the diaphragms for possible ruptures or leaks
 

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 follow all assembly and adjustment procedures.

Before performing any service on the carburetor, it is essential that it be placed on a suitable holding fixture, such as tool J-9789-118, BY-30-15 or equivalent. Without the use of the holding fixture, it is possible to damage throttle valves or other parts of the carburetor.

 
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