Vapor Lock Bulletins
 

These are the various dealer bulletins for vapor lock problems recommending the addition of the helper fuel pumps and the "famous" carburetor blower fan.

84-124 REVISED TESTING PROCEDURE FOR CANISTER CONTROL VALVE
 

Number:84-124
Section:6E
Date:May, 1984
Subject:REVISED TESTING PROCEDURE FOR CANISTER CONTROL VALVE
Model and Year:1982-84 CAPRICE, CAMARO, MONTE CARLO AND MALIBU WITH EITHER 3.8L V6, 4.4L V8, 5.0L V8 OR 5.7L V8
To:All Chevrolet Dealers

This bulletin supercedes 83-29 issued in December, 1982.<P>When diagnosing a condition such as rough idle, rich acceleration, or lean idle duty cycles (indications of rich carburetion), the following procedure should be followed for diagnosis of a canister control valve:

NOTICE: The canister control valve must be removed from the vehicle to perform this test.

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1. Apply a short length of 3/8" (9.5 mm) I.D. hose to the carburetor bowl tube of the canister control valve (see illustration) and blow into it. Air should pass out through the canister tube. If it does not, replace the canister control valve.

2. Use a hand vacuum pump to apply vacuum (15" Hg or 51 kPa) to the PCV tube. The diaphragm should hold vacuum for at least twenty (20) seconds. If it does not, replace the canister control valve.

3. With vacuum still applied, again try to blow through the hose into the carburetor bowl tube. No air should flow from the canister tube. If it does, the lower valve assembly is not sealing correctly, and the canister control valve must be replaced.

4. Remove the short hose from the carburetor bowl tube, and install it on the canister tube. Move hand vacuum pump to apply vacuum (15" Hg or 51 kPa) to the control vacuum tube, permitting vacuum to raise the upper diaphragm. The diaphragm should hold the vacuum for at least twenty (20) seconds. If it does not, replace the canister control valve.

5. Seal the carburetor bowl tube with a rubber cap or finger, and while vacuum is still being applied to the control vacuum tube, try to blow through the hose connected to the canister tube. Air should pass freely from the PCV tube. If not, the canister control valve must be replaced.

84-172 REDUCTION IN PERFORMANCE UNDER HARD ACCELERATION ON 5.0L B8 4BBL ENGINES (LG4)
 

Number:84-172
Section:6C
Date:July, 1984
Subject:REDUCTION IN PERFORMANCE UNDER HARD ACCELERATION ON 5.0L B8 4BBL ENGINES (LG4)
Model and Year:1982-84 CAMARO
To:All Chevrolet Dealers

Some Camaros with the LG4 engine may experience a reduction in performance in the form of hesitation or sag under hard acceleration. This condition usually occurs at high ambient temperatures when the engine is hot and may be due to fuel vapor lock. Vapor lock is temporary fuel starvation that is most likely to happen upon acceleration after a short soak or extended idle period.

To alleviate this condition, it will be necessary to replace the fuel pump with service kit, P/N 6472366. This new pump utilizes a smaller return line orifice.

Pumps that may require replacement can be identified by the last five (5) digits of the part number stamped on the bottom side of the pump mounting flange. They are as follows:

Vehicle Year 1982
I.D. Number 42076
Vehicle Year Interim 1982, All 1983-84
I.D. Number 41265

Follow replacement procedures as outlined in the appropriate Camaro shop manual.

84-174 REDUCTION IN PERFORMANCE UNDER HARD ACCELERATION ON 5.0L HIGH OUTPUT V8 4BBL E
 

Number: 84-174
Section: 6C
Date: July, 1984
Subject: REDUCTION IN PERFORMANCE UNDER HARD ACCELERATION ON 5.0L HIGH OUTPUT V8 4BBL ENGINES (L69)
Model and Year:1983-84 CAMARO
To: All Chevrolet Dealers

Some Camaros with the L69 engine may experience a reduction in performance in the form of hesitation or sag under hard acceleration. This condition usually occurs at high ambient temperatures when the engine is hot and may be due to fuel vapor lock. Vapor lock is temporary fuel starvation that is most likely to happen upon acceleration after a short soak or extended idle period.

To repair this condition, it will be necessary to install vapor lock fix kit, P/N 14085385. This kit utilizes a low pressure (3 psi) electric in-tank pump.

The fuel vapor fuel fix kit has detailed instruction sheets for installing all parts found in the kit and for reworking existing grommets on the vehicle. The instruction sheets do not show parts that have to be removed in order to install kit parts. Use the appropriate shop manual procedures where indicated.

1. Disconnect battery.

2. Remove fuel tank to install new pump and sending unit (ref. 1983 Camaro Shop Manual - 6C-5 and 6C-6).

CAUTION: Care should be taken when removing exhaust pipe bolts from the converter flange to avoid breaking the bolts.

NOTICE: New fuel feed, return and vent hoses must be changed because of material composition.

3. The following interior trim items must be removed to install new body wire harness assembly into existing harness conduit (under carpeting) and into instrument panel connector.

A. Remove instrument panel sound absorber (hush panel) L.H. (ref. 1983 Camaro Shop Manual 83C-2).

B. Remove shroud side trim finishing panel - L.H. (ref. 1983 Camaro Shop Manual - Body Section 4-1).

C. Remove sill plate and carpet retainer - L.H.

D. Remove body lock pillar trim finishing panel - L.H. (ref. 1983 Camaro Shop Manul - Body Section 6-1).

E. Remove spare tire trim finishing panel (ref. 1983 Camaro Shop Manual - Body Section 6-2).

F. Remove rear trim panel (ref. 1983 Camaro Shop Manual - Body Section 7-9).

G. Remove quarter lower trim finishing panel L.H. (ref. 1983 Camaro Shop Manual - Body Section 6-1).

H. Remove quarter upper trim finishing panel - L.H. (ref. 1983 Camaro Shop Manual - Body Section 6-2).

4. Remove L.H. tail lamp assembly to route the body harness assembly from under body to passenger compartment (ref. 1983 Camaro Shop Manual - Body Section 7-12).

NOTICE: The tail lamp assembly wiring does not need to be disconnected.

5. The following underhood operations must be performed to install the new fuel pump and oil pressure switch assembly, fuel pump harness assemble, and fuel pump relay assembly.

A. Remove air cleaner.

B. Disconnect brake vacuum pipe at rear of carburetor.

C. Disconnect throttle cable and springs.

D. Disconnect throttle cable bracket.

E. Remove oil pressure sending unit.

NOTICE: New fuel feed and return hoses (at pump) must be changed because of material composition. If vehicle is not equipped with rear window washer option, remove existing body plug and install grommet supplied in kit (ref. instruction sheet #4, View C).

6. Reassemble all parts removed and reconnect battery.

7. Perform electrical check per instruction sheet #6.

NOTICE: If pump does not work, check the two (2) in-line fuses in the new jumper harness assembly.

8. Check for oil leaks at oil sender unit.

84-230 WIRING DIAGRAMS FOR ELECTRIC FUEL PUMP ON 5.0L HIGH OUTPUT V8 ENGINES (L69)
 

Number: 84-230
Section: 6C
Date: Jan., 1985
Subject: WIRING DIAGRAMS FOR ELECTRIC FUEL PUMP ON 5.0L HIGH OUTPUT V8 ENGINES (L69) VIN ENGINE IDENTIFICATION 1983(7), 1984(G)
Model and Year: 1983-84 CAMARO Z28
To: All Chevrolet Dealers

The following wiring diagrams should be used in the diagnosis of the subject vehicles equipped with electric fuel pumps.

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This diagram should be used in the diagnosis of any 1983 or 1984 vehicle where the service kit, P/N 14085385, has been installed per Chevrolet Dealer Service Bulletin 84-174.

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This diagram should be used on 1984 vehicles produced after the following VIN numbers:

Norwood: EN163862
Van Nuys: EL194637

86-222 ENGINE SURGE AFTER A HOT SOAK
 

Number: 86-222
Section: 6C
Date: Feb., 1987
Subject: ENGINE SURGE AFTER A HOT SOAK
Model and Year: 1983-86 CHEVROLET PRODUCED V-8 PASSENGER CARS WITH E4ME QUADRAJET 4BBL CARBURETORS
To: All Chevrolet Dealers

This bulletin cancels and supercedes Dealer Service Bulletin 86-60 Reissue (Section 6C) dated Dec., 1986. All copies of 86-60 Reissue should be destroyed, it did not include steps 8 or 9 of the reassembly procedure. Replacement of carburetor primary metering jets is covered under the 5 year/50,000 mile emission warranty.

Customer comments of engine surge after a hot soak may be received. A hot soak is when the vehicle has reached operating temperature, then parked for a short time and restarted. The surge is caused by excessive fuel vapor in the carburetor bowl. This fuel vapor is created by the temperature difference of the carburetor bowl and the fresh fuel delivered from the fuel tank on a restart. This surge condition can be reduced by installing new design primary metering jets in the carburetor.

Part Numbers of Carburetors Affected:

17059320
17083218
17085202
17086004
17059322
17084201
17085203
17086005
17083204
17084205
17085204
17086006
17083205
17084208
17085207
17086040
17083206
17084209
17085218
17083207
17084210
17086003

Primary Metering Jet Replacement:

Refer to appropriate vehicle service manual (Section 6C1) for carburetor disassembly and adjustment information.

NOTICE: REPLACING THE PRIMARY METERING JETS IN THE E4ME CARBURETOR REQUIRES REMOVING THE MIXTURE CONTROL SOLENOID AND THE FLOAT. THEREFORE THE ADJUSTMENTS AFFECTING THESE COMPONENTS MUST BE CHECKED AND ADJUSTED, IF NECESSARY DURING REASSEMBLY. THE FOLLOWING STEPS SHOULD BE FOLLOWED AS A GENERAL GUIDE TO THE REPLACEMENT OF THE METERING JETS.

Disassembly
1. Remove air cleaner.
2. Remove air bleed valve cover.
3. Remove air horn.
4. Remove solenoid adjusting (lean stop) screw and solenoid (rich stop) screw plugs.
5. Remove mixture control solenoid assembly.

NOTICE: IF TOOL #J33815-1 OR EQUIVALENT IS NOT USED FOR REINSTALLING MIXTURE CONTROL SOLENOID, IT WILL BE NECESSARY TO RECORD NUMBER OF TURNS WHEN REMOVING ADJUSTING (LEAN STOP) SCREW.

6. Remove float.
7. Remove primary metering jet assemblies.

Reassembly
1. Install new primary metering jet assemblies.
2. Install float and adjust if necessary. The specification for float level is 11/32".
3. Install mixture control solenoid using tool, #J33815-1 or equivalent or by setting adjusting (lean stop) screw to the same number of turns recorded in step #5 of Disassembly.
4. Install air horn with new gasket.
5. If carburetor has a removable pump lever hinge pin, install the cotter pin supplied in air horn gasket, following package instruction.
6. Check mixture control solenoid plunger travel: should be 4/32". If not, adjust solenoid (rich) stop screw to obtain correct travel
7. Install solenoid adjusting (lean stop) and solenoid (rich) stop screw plugs.
8. Check mixture control solenoid dwell with engine running in closed loop and canister purge disconnected. Dwell should read approximately 30 at idle. If not, adjust air bleed valve to obtain.
9. Reconnect canister purge and install air cleaner housing.

Parts Required

17082634 - Jet Assemblies - One pkg. required.
17067279 - Air Horn Gasket - One pkg. required.

NOTICE: THESE METERING JETS CAN ALSO BE USED WITH CARBURETOR BLOWER FANS ON "F" CARS (REF:CHEVROLET BULLETIN 86-35).

86-238 DRIVEABILITY - WARM HESITATION
 

Number: 86-238
Section: 6E
Date: May, 1986
Subject: DRIVEABILITY - WARM HESITATION
Model and Year: 1982-86 PASSENGER CARS WITH 5.0L (V.I.N. CODE H) ENGINE
1984-86 PASSENGER CARS WITH 5.0L (V.I.N. CODE G) ENGINE
To: All Chevrolet Dealers

Some vehicles with the above engines may experience a hesitation on light acceleration. This hesitation is normally seen after an extended idle or a short hot soak in higher ambient temperatures. This condition could be caused by excessive fuel vapor entering the engine through the canister purge system. To determine if the hesitation is from the purge system the following test should be performed:

1. Vehicle should be at normal operation temperature.

2. On 1982-85 models plug canister purge at Y connector in crankcase vent line. On 1986 models plug canister purge at carburetor.

3. Test Drive Vehicle

a. Hesitation still present, look for other reasons for hesitation (accelerator pump, timing, etc.).

b. Hesitation no longer present, install fuel vapor canister control kit, P/N 10077501 per instruction in kit.

4. Reconnect purge system.

86-242 HOT FUEL HANDLING - ENGINE SURGE AFTER HOT SOAK
 

Number: 86-242
Section: 6C
Date: June, 1986
Subject: HOT FUEL HANDLING - ENGINE SURGE AFTER HOT SOAK
Model and Year: 1983-86 CAMARO WITH 5.0L, V-8 4BBL ENGINE
To: All Chevrolet Dealers

Customer comments of engine surge after hot soak may be received. A hot soak is when a vehicle has reached normal operating temperature, then parked with engine off for a short time, and then restarted and immediately driven. The hot soak condition is more evident with higher ambient temperatures and the resultant engine surge is caused by excessive fuel vapor in the carburetor bowl. This fuel vapor is created by the temperature difference betwen the carburetor bowl and the fresh fuel coming from the fuel tank upon restart. Another source of excessive fuel vapor is the charcoal canister which has become saturated during the hot soak.

The following is a suggested sequence for diagnosing and repairing driveability comments stemming from a hot soak condition.

1. Determine that surge is not due to mechanical problem and/or misadjustments; carburetor float level, fuel delivery, thermac operation, ignition timing, etc.

2. If it has been determined that the vehicle meets specifications and hot soak surge is still present, proceed to step #3.

3. Install carburetor primary metering jets per Bulletin 86-60 Reissue Sec. 6L. Superceded by 86-222 above.

4. Road test vehicle for surge after hot soak. If surge is still present, proceed to step #5.

5. Install evaporative canister vacuum control harness P/N 10077501 per Bulletin 86-238 Sec. 6E.

6. Road test vehicle for surge after hot soak. If surge is still present, proceed to step #7.

7. Install auxiliary blower fan kit P/N 14094394 per Bulletin 86-35 Sec. 6C. Superceded by 87-131 below

87-131 HOT FUEL HANDLING
 

Number: 87-131
Section: 6C
Date: May, 1987
Subject: HOT FUEL HANDLING
Model and Year: 1983-85 CAMARO WITH L69 ENGINES (VIN CODE G OR H)
1983-87 CAMARO W/MANUAL TRANS. AND LG4 ENGINES (VIN CODE H)
To All Chevrolet Dealers

This Bulletin cancels and supercedes Chevrolet Dealer Service Bulletin 86-34 (Section 6C) dated February, 1986. Expanded year and model coverage along with a notice on reversed wiring connectors are the reason for cancelling 86-35.

Customer comments of vehicle surge, hesitation, and/or stumbles after the vehicle has reached operating temperature, then parked and restarted, (Hot Soak) may be received. This condition is caused by a large temperature difference between the carburetor fuel bowl and the fuel delivered from the fuel tank. This condition may be addressed by installing an auxiliary blower fan, which reduces the temperature of the fuel bowl during a hot soak. The fan is designed to operate at an engine coolant temperature of 220 degrees Fahrenheit (106 degrees C) and stay operational until the coolant reaches 195 degrees Fahrenheit (90 degrees C). This will maintain a fuel bowl temperature of approximately 165 degrees Fahrenheit (74 degrees C).

Listed below is the Hot Fuel Handling service kit part number:

P/N: 14094394
Usage: Camaro


Notice: Some kits have been reported with the two wires at the blower motor connector reversed. This causes the blower motor to run backwards, resulting in reduced airflow to the carburetor. This reduced airflow may not adequately address the hot fuel condition.

Beginning with the 1987 model year, vehicles produced with LG4 engine and manual transmissions have auxiliary fans.

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When installing kits or investigating hot fuel problems, check for the proper indexing of the wiring connector per attached illustration. In each kit there is a one page flyer explaining the blower kit operation. Please ensure that the customer receives this flyer.