Carburetor - Rochester e2se/2se 2-bbl Pontiac 6000 I

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during REMOVAL & INSTALLATION or OVERHAUL procedures

APPLICATION

2.8L GENERAL MOTORS (ROCHESTER) CARBURETOR NO.

IDENTIFICATION

The Rochester E2SE carburetor numbers are stamped vertically on the float bowl. If float bowl is replaced, follow manufacturer's instructions contained in service package to transfer part number to new float bowl.

Carburetor Identification Label Original part number must be transferred from old float bowl if new float bowl is installed. Scheme 1

DESCRIPTION

The Rochester Varajet Carburetor E2SE is a 2-barrel, 2-stage downdraft carburetor used with the Computer Command Control fuel control system. An electrically-operated mixture control solenoid, mounted in the air horn and extending into the float bowl, controls the air/fuel mixture in the primary bore. In the secondary bore, an air valve, and a tapered metering rod operating in a fixed jet, control the air/fuel mixture during increased engine airflow at wide open throttle.

The carburetor comprises 3 major assemblies: air horn, float bowl and throttle body. A single float chamber supplies fuel to both bores. A float, needle seat, and needle, with pull clip and float bowl inserts, help control the level of fuel in the float chamber. On some models, a float stabilizer spring adds further control of fuel level for vehicles used in rugged terrain.

The accelerator pump circuit uses a temperature compensator valve, containing a heat sensitive snap disc. It is pressed into the air horn casting. During cold engine start-up, the pump delivers a full charge to the primary bore. At temperatures above 115°F (46°C), the temperature compensator valve opens, allowing some fuel to be pumped back into the float chamber.

An electrically-heated choke thermostat is used to control choke valve closure during cold start-up, and for choke valve opening during warm-up. There are 2 vacuum break assemblies which control initial choke valve opening at start and during warm-up. A fast idle cam acts as a variable throttle stop to provide increased idle speed during warm-up. To purge the engine if flooded, a throttle lever unloader tang forces the choke valve open. It also operates during wide open throttle position.

All models are equipped with a Throttle Position Sensor (TPS) to signal the ECM of throttle position changes. As changes occur, a tang on the accelerator pump lever moves the TPS plunger, changing the signal to the ECM, to control various engine operating modes.

An Idle Speed Device, either an Idle Stop Solenoid (ISS) or a Throttle Lever Actuator (TLA) is used to position the primary throttle valve to provide engine idle speed requirements.

The electrically operated Mixture Control Solenoid Assembly (MCSA) has 2 separate circuits which control fuel delivery from both idle and main metering systems. The MCSA operates in response to commands from the ECM which turns the solenoid on and off 10 times per second. The solenoid assembly contains a plunger with a valve at each end. The upper valve controls air entering the idle circuit. The lower valve controls part of the fuel entering the main metering circuit.

The Rochester E2SE carburetor used on 2.8L (VIN X) engines uses a temperature compensated pump system. When the engine is cold, more fuel is needed to insure a smooth transition from idle to part throttle. When the engine is warm, less fuel is needed. The system is controlled by the temperature compensator valve, pressed into the air horn, which contains a heat sensitive snap disc. During cold engine start-up, the pump delivers its full capacity to the primary bore. At operating temperature, the temperature compensator valve opens, allowing some fuel to be pumped back into the float bowl.

Note. No attempt should be made to set curb idle speed with the Idle Stop Solenoid.

All carburetors are equipped with tamper-resistant features: Factory-adjusted rich mixture screws, factory-adjusted lean mixture screws, riveted choke coil housing and hardened steel pump lever. All models are also equipped with idle mixture screw plugs.

ELECTRIC CHOKE

1. Allow choke stat to stabilize at approximately 70°F (21°C). Open throttle, allow choke valve to close. Start engine, determine length of time for choke valve to reach full open position.
2. If longer than 5 minutes, check voltage at choke stat connector, with engine running. If voltage is between 12 and 15 volts, check for proper ground between choke cover and choke housing. If correct, replace choke cover assembly.

VACUUM BREAK

1. If vacuum break has an air bleed hole, plug air bleed hole. Use Special Tools (J 23738 A or BT 7517) and hand operated vacuum pump. Apply 15 in Hg. vacuum to vacuum break.
2. Apply finger pressure to plunger to see if it has moved through full travel. If not, replace vacuum break. If vacuum break does not hold vacuum for at least 20 seconds, replace vacuum break. Replace vacuum break hoses that are cracked, cut or brittle.

MIXTURE CONTROL SOLENOID

Note. Mixture control solenoid must be removed from carburetor to inspect and test.

1. The rubber seal at lower end of solenoid must be free of any cuts, nicks or cracks. Also the rubber seal must not be shrunk of hardened. A new rubber seal and retainer should be installed.
2. Install spacer and new seal on mixture control solenoid stem, making sure seal is up against spacer. Using a 3/16" socket and light hammer, carefully drive new retainer on stem, so that there is a slight clearance between the retainer and the seal to allow for seal expansion.
3. The mixture control solenoid can be checked for a sticking plunger or a leaking fuel valve. With mixture control solenoid removed, connect electrical connector (harness on vehicle) with solenoid removed from carburetor.
4. Ground dwell terminal (Green connector). Connect vacuum pump to end of solenoid. Select rubber hose that will snugly fit over rubber seal. With ignition on and engine stopped, this energizes solenoid (lower end of plunger sealed).
5. Apply approximately 10 in. Hg of vacuum (maximum) and hold. If vacuum won't hold for at least 5 seconds, replace solenoid. Disconnect ground from dwell lead and vacuum gauge reading should instantly go to zero. Replace solenoid if stuck in down position.
6. If functional checks indicate a good mixture control solenoid but calibration problems continue, there will be concealed wear or damage to the fuel control end of the solenoid plunger. Replace solenoid assembly.

ADJUSTMENTS

Note. For on-vehicle adjustments not covered in this article, see appropriate TUNE-UP article.

ANGLE GAUGE ADJUSTMENT TOOL

Manufacturer recommends that some carburetor adjustments be performed using a Choke Valve Angle Gauge (Kent-Moore Tool No. J-26701). While preparations and actual adjustments may vary with each individual adjustment, the procedure for using the angle gauge to check the choke valve angle remains the same. Use the following procedure to perform adjustments requiring the use of the choke angle gauge. (Scheme 2)

Choke Valve Angle Gauge This gauge must be used to perform some adjustments. Scheme 2

1. Close choke valve and place angle gauge magnet squarely on choke valve. Rotate degree scale on angle gauge so that 0° mark is opposite pointer. Rotate leveling bubble on angle gauge until it is centered.
2. Rotate degree scale until specified degree mark is opposite pointer. Now perform individual adjustment preparation as outlined in the following carburetor adjustments requiring an angle gauge.
3. If bubble is centered, adjustment is correct. If not, adjust carburetor as outlined in adjustment procedure.

FLOAT LEVEL (WET SETTING)

Note. This is an on-vehicle adjustment.

Scheme 3

1. Remove air horn vent stack and screen. If using Float Gauge (J 9789-135), remove air horn screw next to open vent. If using Float Gauge (BT 8104), removal of screw is not necessary. (Scheme 3) (Scheme 3): Wet Float Level Adjustment Allow float gauge to float freely.
2. With engine running at idle, choke valve wide-open, insert gauge in bridge or guide hole. Gauge Tool (J 9789 135) has a tang which fits into screw hole to hold gauge upright. Gauge Tool (BT 8104) requires use of the bridge to hold gauge upright. Allow float gauge to float freely. (Scheme 3) NOTE: Pressing down on float gauge could result in float damage or carburetor flooding.
3. With gauge floating freely, observe mark on gauge which aligns with top of casting or bridge (at eye level). Reading should be within 1/16" of specified float level. Incorrect fuel pressure will affect fuel level.
4. If reading is not within 1/16" of specified float level, remove carburetor. Remove air horn and perform FLOAT LEVEL (DRY SETTING) adjustment.

Scheme 4

1. Remove air horn and gasket from float bowl. Attach Float Gauge (J 34817 1 or BT 8227A 1) to float bowl. Place Gauge Tool (J 34817 3 or BT 8227 A) in base, with contact pin resting on outer edge of float lever. (Scheme 4) (Scheme 4): Dry Float Level Adjustment Tool placement is shown.
2. Using Float Gauge (J 9789 90 or BT 8037), measure distance from top of float bowl casting to top of float, at point farthest from float hinge.
3. If measurement is more than 2/32" (1.6 mm) from specification, use Bending Tool (J 34817 20 or BT 8045 A) to bend lever up or down.
4. Remove bending tool and remeasure setting. Repeat until within specification. Visually check float alignment and reassemble carburetor.

Scheme 5

1. Remove intermediate choke rod to gain access to lock screw, if required. Using an 3/32" Allen wrench, loosen air valve lock screw. Using a screwdriver, turn tension adjusting screw clockwise until air valve opens slightly. (Scheme 5) (Scheme 5): Air Valve Spring Adjustment Remove intermediate choke rod to gain access to lock screw, if required.
2. Turn tension adjusting screw counterclockwise until air valve just closes. Turn adjusting screw additional specified turns (counterclockwise).
3. Tighten air valve lock screw. Coat air valve shaft pin and closing spring contact areas with lithium base grease.

CHOKE COIL LEVER

Note. DO NOT remove rivets and retainers holding choke cover and coil assembly in place unless necessary to check choke coil lever adjustment. If rivets and cover are removed, a new rivet service kit must be installed.

Scheme 6

1. Remove rivets and choke thermostatic cover from choke housing. Place the fast idle screw on high step of the fast idle cam. (Scheme 6) (Scheme 6): Choke Coil Lever Adjustment Bend rod to adjust.
2. Push on intermediate choke lever until choke valve is fully closed.
3. Insert a.085" (2.2 mm) drill or plug gauge into hole provided in choke housing. Edge of choke lever inside housing should just touch drill or plug gauge.
4. To adjust, support intermediate choke link at "S" in (Scheme 6) and using Bending Tool (J 9789 111 or BT 3006 M), bend intermediate choke link. Reinstall choke cover and adjust.

CHOKE ROD (FAST IDLE CAM)

Note. Choke coil lever adjustment must be correct before proceeding. This adjustment makes use of choke angle gauge. See procedure at beginning of ADJUSTMENTS.

Scheme 7

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close. Set up angle gauge and set to specified angle.
2. Place fast idle speed screw on second step of fast idle cam against shoulder of highest step. (Scheme 7) Push on choke shaft lever to open choke valve and to make contact with closing tang. (Scheme 7): Choke Rod (Fast Idle Cam) Adjustment Bend rod to adjust.
3. To adjust, support fast idle cam rod at "S" and bend fast idle cam rod until bubble of choke valve angle gauge is centered. (Scheme 7)

PRIMARY VACUUM BREAK

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of ADJUSTMENTS.

Scheme 8

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close.
2. Set up angle gauge and set angle to specification. Using a vacuum source of at least 18 in. Hg, retract vacuum break plunger and plug air bleed hole. (Scheme 8) NOTE: Air valve linkage must not restrict vacuum plunger from retracting fully. If necessary, support at "S". (Scheme 8) Bend linkage to permit full plunger travel. Final linkage clearance must be set after vacuum break setting has been made. If equipped, ensure plunger bucking spring is compressed and seated (plunger fully extended). (Scheme 8): Primary Vacuum Break Adjustment Turn screw or bend rod with vacuum still applied.
3. To adjust on models with hex-head adjustment, use a 1/8" hex wrench to turn screw in rear cover until bubble is centered. Apply RTV silicone sealant over screw head to seal setting. To adjust on models without hex-head adjustment, support vacuum break rod and bend rod with vacuum still applied. (Scheme 8)

AIR VALVE ROD

Note. This adjustment is made by using the choke valve angle gauge. See procedure at beginning of ADJUSTMENTS.

Scheme 9

1. Set up angle gauge on air valve and set specified angle. Using an outside vacuum source of at least 18 in. Hg, seat primary choke vacuum break diaphragm plunger. (Scheme 9) (Scheme 9): Air Valve Rod Adjustment Bend rod to adjust. NOTE: Plug end cover on models with primary vacuum break only, using tape or accelerator pump plunger cup. Cup must be removed after adjustment is completed.
2. Rotate air valve in direction of open air valve by applying light pressure to air valve lever. To adjust, support air valve rod and set to specified angle by bending rod until bubble on gauge is centered.

AUTOMATIC CHOKE

Choke coil cover is retained on housing with rivets to prevent tampering with factory adjustment. If necessary to remove cover, refer to DISASSEMBLY and REASSEMBLY procedures.

SECONDARY VACUUM BREAK

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of ADJUSTMENTS.

Scheme 10

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close.
2. Set up angle gauge and set angle to specification. Using an outside vacuum source of at least 18 in. Hg, retract vacuum break plunger. (Scheme 10) (Scheme 10): Secondary Vacuum Break Adjustment Turn screw or bend rod with vacuum still applied.
3. Where applicable, plug air bleed holes and ensure plunger stem is fully extended to compress plunger bucking spring.
4. To adjust on models with hex-head adjustment, use a 1/8" hex wrench to turn screw in rear cover until bubble is centered. Apply RTV silicone sealant over screw head to seal setting. To adjust on models without hex-head adjustment, support vacuum break rod and bend rod with vacuum still applied. (Scheme 10)

CHOKE UNLOADER

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of ADJUSTMENTS.

Scheme 11

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close. (Scheme 11) (Scheme 11): Choke Unloader Adjustment Bend choke unloader tang to adjust.
2. Set up angle gauge and set to specified angle. Hold throttle lever in wide open position.
3. Push on choke shaft lever to open choke valve and to make contact with closing tang. To adjust, bend tang on throttle lever until bubble is centered.
4. Remove gauge and reinstall choke cover and coil assembly if previously removed. Install service rivet and retainer kit.

Scheme 12

1. Hold choke valve wide open by pushing down on intermediate choke lever. (Scheme 12) (Scheme 12): Secondary Throttle Lock-Out Adjustment Bend lock-out lever to adjust.
2. Open throttle lever until end of secondary actuating lever is opposite toe of lockout lever.
3. Measure specified clearance between end of actuating lever and toe of lock-out lever. Measurement can be checked using a drill or pin gauge of specified size.
4. To adjust, bend the lockout lever tang contacting the fast idle cam.

DISASSEMBLY

Note. Before disassembling carburetor, mount unit in a suitable holding fixture to prevent damage to throttle valves or linkage.

Air Horn

1. Remove idle stop solenoid/primary vacuum break bracket retaining screws. Remove bracket assembly. Disengage vacuum break link from slot in choke lever. Lift and rotate bracket assembly to remove air valve rod from slot in air valve lever.
2. Remove secondary vacuum break bracket attaching screws. Rotate bracket assembly to disengage vacuum break link from choke lever slot. CAUTION: DO NOT remove pump lever retaining screw.
3. Remove and discard retaining clip from intermediate choke rod at choke lever. Use a new retaining clip during reassembly. Remove choke rod and plastic bushing from choke lever. Bushing may be reused.
4. Remove 3 mixture control solenoid screws and remove mixture control solenoid using a light twisting motion. Remove and discard solenoid gasket, plunger seal and plunger seal retainer.
5. Remove all air horn-to-float bowl screws and lock washers. Remove vent stack and screen assembly. Rotate fast idle cam up as far as possible. Rotate air horn and tilt to disengage fast idle cam rod from slot in fast idle cam and pump rod from pump lever hole. NOTE: If pump plunger comes out of float bowl with air horn removal, remove pump plunger from air horn. Air horn gasket should remain on float bowl. DO NOT remove fast idle cam screw and cam from float bowl. These parts must remain permanently in place as installed by manufacturer. Service replacement float bowl will include fast idle cam screw and cam.
6. Disconnect fast idle cam rod from choke lever by aligning tang on rod with slot in lever. Lift off air horn assembly.
7. Remove TPS plunger by pushing downward through seal in air horn. Remove seal retainer and seal. Remove accelerator pump plunger seal from air horn after using a small screwdriver to remove staking around each seal retainer. NOTE: Use fingers only (no tools) when removing plunger to prevent damage to sealing surface. Use care in removing plunger seal retainer and plunger stem seal retainer to prevent damage to air horn. Discard seals and retainers.
8. No further disassembly of air horn is required. Air valve and choke valve attaching screws are staked in place and are not removable. New service replacement air horn assembly includes secondary metering rod and air valve assemblies with preset factory adjustments. No attempt should be made to change air valve settings.

Float Bowl

1. Remove air horn gasket. Remove pump plunger and pump spring from pump well. Remove plastic filler block from float valve.
2. Remove float assembly and float valve, pulling up on retaining pin. If equipped, remove float stabilizing spring with float assembly. Remove float needle seat, gasket and extended metering jet from float bowl. Use jet tool or screwdriver that fully fits slot in top of jet. NOTE: DO NOT remove or adjust small calibration screw located deep inside metering jet. Adjustment should be made only if required by a Computer Command Control System performance check.
3. Push up from bottom on electrical connector and remove TPS and connector from float bowl. Remove spring from bottom of TPS well in bowl.
4. Remove main metering jet using a screwdriver that fits tight in groove. Using a small slide hammer, remove plastic retainer holding pump discharge spring and check ball in place in float bowl. Discard retainer.
5. To remove choke cover and coil assembly, align a .159" (No. 21) drill on choke cover retaining rivet. Drill only enough to remove rivet heads. Remove rivets, choke cover and coil assembly. Remove screw from end of intermediate choke shaft in choke housing. Remove choke coil lever from shaft.
6. Slide intermediate choke shaft out of float bowl. Remove choke housing screws and remove choke housing. Remove fuel inlet nut, gasket, check valve/filter and spring.
7. Remove 4 screws securing throttle body to float bowl. Remove throttle body. Remove throttle body insulator gasket.

Throttle Body

1. Hold throttle valves wide open. Disengage pump rod from throttle lever by rotating rod until tang on rod aligns with slot in lever.
2. Remove curb idle and fast idle speed screws and springs if necessary. Further disassembly of throttle body is not required. Throttle valve screws are permanently staked in position. NOTE: DO NOT remove idle mixture screw plug unless it is necessary to replace mixture screw, or if cleaning and air pressure fails to clean idle mixture passages. If necessary to remove, proceed as follows
3. Invert throttle body and position on a holding fixture with manifold side up. Using a small hacksaw, make 2 small cuts, one on either side of mixture screw plug location. Position a small flat punch on throttle body between cuts.
4. Drive punch down and break out portion of throttle body between the 2 cuts. Hold punch at a 45° angle and drive out hardened steel plug. NOTE: Plug will shatter when struck. Remove loose pieces to allow the use of mixture adjusting tool or thin-walled deep 3/16" socket to remove adjusting screw and spring.
5. Turn mixture screw in carefully, counting turns needed to seat screw. Record number to be used in reassembly, then remove mixture screw.

IDLE MIXTURE SCREW CHART

CLEANING & INSPECTION

1. DO NOT soak any components containing rubber, leather or plastic. Definitely do not soak idle speed solenoid, mixture control solenoid, throttle position sensor, electric choke, diaphragms, pump plunger and plastic filler block. Plastic bushings will withstand normal cleaning.
2. Use a regular carburetor cleaning solution. Soak components long enough to thoroughly clean all surfaces and passages of foreign matter. Remove any residue after cleaning by rinsing components in a suitable solvent.
3. Blow out all passages with dry compressed air. Test mixture control solenoid for sticking, binding or leaking. Connect jumper wire between battery positive terminal and right (positive) solenoid terminal.
4. Connect another jumper wire between battery negative terminal and left (negative) solenoid terminal. Remove rubber seal and retainer from solenoid stem and attach hand vacuum pump and gauge. (Scheme 14)
5. Apply 25 in. Hg of vacuum. Time leak-down rate from 20 in. Hg to 15 in. Hg. If time exceeds 5 seconds, replace solenoid. Remove jumper wires. Apply 15 in. Hg of vacuum. Vacuum should drop to zero in less than 1 second. If not, replace solenoid.

Exploded View of Rochester E2SE 2-Barrel Carburetor. Scheme 13

Testing Mixture Control Solenoid (Removed From Carb.) Connect to battery voltage for testing. Scheme 14

REASSEMBLY

Note. Use new gasket and seals. Make sure new gaskets fit correctly and all holes are punched through and properly located.

Scheme 15

1. To reassemble carburetor, reverse disassembly procedure. Install fuel inlet needle pull clip over edge of flat on float arm facing float. DO NOT hook clip in holes in float arm.
2. After throttle body is installed on float bowl, make sure secondary lock-out tang is in correct position to engage secondary lock-out lever. DO NOT pull clip through slots in lever.
3. Use Seating Tools (J 28696 10 or BT 7928) to lightly seat needle, then back out the number of turns counted in disassembly. Make final mixture adjustment on the vehicle.
4. Install new accelerator pump discharge check ball and spring plastic retainer. Insert end of retainer in spring and place in position in float bowl. Lightly tap retainer into position until it is flush in float bowl.
5. Make sure holes in fuel filter face toward fuel inlet fitting when filter is installed.
6. Some linkage retaining clips are dished. Make sure portion of clip that bends outward is toward end of rod. Make sure clip makes full contact with rod.
7. Place fast idle screw on high step of fast idle cam. Install choke coil cover, aligning notch in cover with raised boss on housing cover flange. NOTE: If choke cover and coil assembly was removed from housing, a service rivet kit must be installed to restore tamper-resistant feature. CAUTION: Be sure coil pick-up lever is located inside choke coil tang. Also, on electric chokes, the ground contact is provided by a metal plate at rear of choke cover assembly. DO NOT install a choke cover gasket between electric choke assembly and choke housing.
8. Mixture control solenoid connector must be installed with Pink wire on right-hand terminal of connector, as viewed from harness end. On some models, the connector latch may require minor filing to allow proper latching.
9. When installing air horn assembly, be sure that tubes are positioned properly through holes in air horn gasket. Guide pump stem through seal. Install air horn screws, noting location and type of screw for correct installation. Tighten screws evenly, securely and in proper sequence. (Scheme 15) (Scheme 15): Air Horn Screw Location & Tightening Sequence
10. Install mixture control solenoid seal on solenoid stem. Using a 3/16" socket and hammer, lightly tap retainer in place, on stem, leaving a slight clearance between retainer and seal. Apply silicone grease to seal before installation of solenoid.

SPECIFICATIONS

17084534, 17084535, 17084540 CARBURETOR ADJUSTMENT SPECIFICATIONS

17084542 CARBURETOR ADJUSTMENT SPECIFICATIONS

17085006, 17085388, 17086081 CARBURETOR ADJUSTMENT SPECIFICATIONS

17084534, 17084535, 17084540 CARBURETOR ADJUSTMENT SPECIFICATIONS