ON-VEHICLE CLEANING OF PORT FUEL INJECTORS

ALL 1985-86 PORT FUEL INJECTED ENGINES

THIS CANCELS AND REPLACES 85-6(GASOLINE)-51 DATED 10/85 TO REVISE THE PROCEDURE AND LABOR TIME INFORMATION.

If deposits form on the tip of port fuel injectors, the engine may experience rough operation. These deposits reduce fuel flow and cause a lean condition. Analysis of returned injectors have shown a high percentage of good injectors being replaced. THE PURPOSE OF THIS BULLETIN IS TO EMPHASIZE THAT ON-VEHICLE CLEANING SHOULD BE USED INSTEAD OF INJECTOR REPLACEMENT.

ESSENTIAL TOOL:

1. Kent Moore Tool #J-35800 is required.

2. Shipping of tool to dealers started 11/26/85.

3. All dealerships should receive their tool by 12/31/85.

SERVICE PROCEDURE:

1. Identify lean injectors by performing injector balance test as described in the 1986 Service Manual, Section 6E3. If no lean injectors are found, determine the cause of engine roughness and correct. Cleaning may not be necessary.

2. Clean injectors using Kent Moore Tool #J-35800.

NOTICE: TO USE THIS DEVICE THE VEHICLE FUEL SYSTEM MUST HOLD PRESSURE. IF IT DOES NOT HOLD PRESSURE, REPAIR AS REQUIRED. ENGINE MUST BE FULLY WARMED UP AND SHUT OFF BEFORE ATTACHING THIS TOOL.

A. Add approximately 1/2 gallon of mixture of 95% gasoline and 5% cleaner to J 35800 tank.

NOTICE: DO NOT EXCEED THE 5% CONCENTRATION OF CLEANER AS DAMAGE TO THE FUEL SYSTEM MAY RESULT.

USE ONLY APPROVED INJECTOR CLEANING SOLVENTS, SUCH AS, 1050002 GM TOP ENGINE CLEANER OR X66-P AC-DELCO CARBURETOR TUNE-UP CONDITIONER.

B. Attach J35800 hose end to vehicle fuel rail pressure test connection.

C. Pump J 35800 until pressure gauge reads 25 psi.

D. Open J 35800 inline valve 1/2 turn.

E. Disable vehicle in-tank fuel pump.

F. Start and run engine at 2000 rpm until 1 1/2 quarts of solution is used.

- 8 cylinder approximately 10 minutes. - 4 and 6 cylinder approximately 15 minutes.

G. Stop Engine.

H. Close J 35800 inline valve and disconnect J 35800.

I. Recap vehicle test fitting and connect vehicle fuel pump.

J. Immediately run engine for 5 minutes at 1000/2000 rpm to flush cleaner from fuel rail and injectors.

NOTICE: DO NOT ADD THE CLEANER DIRECTLY TO THE VEHICLE GASOLINE TANK AS DAMAGE TO THE FUEL SYSTEM MAY RESULT.

AFTER THE INJECTORS ARE CLEANED, OWNERS SHOULD BE ADVISED THAT USE OF FUELS WITH DETERGENT ADDITIVES SHOULD KEEP THE INJECTORS CLEAN. PREMIUM UNLEADED GASOLINES GENERALLY CONTAIN LOWER LEVELS OF MATERIALS BELIEVED TO FORM DEPOSITS, AND HIGHER LEVELS OF DETERGENTS THAN REGULAR UNLEADED GASOLINES. THEIR OCCASIONAL USE COULD HELP PREVENT FUTURE INJECTOR DEPOSIT FORMATION.

There are encouraging signs that oil companies are addressing deposit formation and will be providing regular and premium unleaded gasolines with higher levels of detergents which can prevent and in some cases even remove injector deposits. This will be a welcome development not only for Pontiac owners, but also for owners of other domestic and foreign cars equipped with port fuel injection system. Local gasoline advertising is one guideline for selecting fuels with high detergent content.

Labor Operation Number: T1143 Labor Time : 1.1 hours

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.