ON VEHICLE CLEANING OF PORT FUEL INJECTORS

VEHICLES AFFECTED: All 1984 Thru 1986 Models Equipped With Port Fuel Injection

We have received some comments on different driveability conditions that were ultimately diagnosed as 'restricted fuel injectors'.

A restricted injector condition may result in any of the following: Lean Surge Engine Miss Tip-in Hesitation T.C.C. Chuggle Cold Start Sag Rough Idle Hard Starting Lack of Power

Restricted injectors may be caused by a build-up of deposits on the pintle of the injector resulting in a lean air/fuel ratio.

In order to determine if fuel injectors are the cause of one of the above conditions, it will be necessary to perform the Fuel System Pressure Test and Injector Balance Test using procedures described in Section 6E3 of the 'Chassis Service Manual'. In most cases, restricted fuel injectors are also indicated by a high integrator/block learn reading during one of the above-listed conditions. (Refer to Bulletin 85-6-126).

There are injector cleaning tools available on the market such as the Kent-Moore J-35800 (expected to be released in Oct. 1985), which make it possible to clean fuel injectors without removing the fuel rail or injectors from the vehicle.

Following equipment manufacturer's instructions for introducing the solution into the fuel pressure gauge test point of the fuel rail, blend a mixture of 95% gasoline and 5% GM Engine Cleaner, Part No. 992872, or AC-Delco Carburetor Tune-Up Conditioner, (X66-P). Use approximately 1.475L (50 ounces) of the solution. (1.4L (three pints) of gasoline and 75ml (2.5 ounces) of GM Top Engine Cleaner or AC-Delco Carburetor Tune-Up Conditioner).

NOTICE: DO NOT EXCEED THE 5% CONCENTRATION AND DO NOT ADD GM TOP ENGINE CLEANER OR AC-DELCO CARBURETOR TUNE-UP CONDITIONER TO VEHICLE GASOLINE TANK, AS DAMAGE TO THE FUEL SYSTEM MAY RESULT.

It appears that some fuels tend to reduce or eliminate restricted injectors more than others, however; the same brand of fuel in different locations of the country may have different results.

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.