INFO ON MULTEC FUEL INJECTORS DO NOT CLEAN MULTEC INJECTORS

SUBJECT: INFORMATION ON MULTEC FUEL INJECTORS/CLEANING

VEHICLES AFFECTED: 1986-1992 CARS AND TRUCKS WITH MULTEC TOP FEED INJECTOR APPLICATIONS

This bulletin has been written to inform technicians of possible damage to Multec injectors as a result of cleaning. The ball and seat design of the Multec injector eliminates the need of ever having to use an injector cleaner. By design, the fuel metering portions of the injector are not directly exposed to the intake manifold gases that are responsible for the build-up of deposits that can cause injectors to clog, as shown in Figure 1.

Some of these cleaners may contain high percentages of alcohol and other solvents that cause damage to the injectors' coil wire insulation. Damaged insulation results in low resistance or shorted injectors. Also, alcohol reduces fuel lubricity which increases friction at the injectors' critical bearing surfaces which results in premature wear.

General Motors has conducted extensive injector cleaning studies to determine effectiveness. There is no confirmed evidence that cleaning Multec injectors has resolved a vehicle driveability problem. In addition, suppliers of various injector cleaners may claim that their product can also clean intake valve deposits. General Motors laboratory tests have shown that injector cleaners have little or no effect on intake valve deposits.

General Motors maintains the position that Multec injectors should not be cleaned.

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.