TSB 91-6-26: Multec Fuel Injectors - Cleaning Information

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91pontiac03 Bulletin Number: 91-6-26 Reference Number: 116502 Publish Date: 2/91 Subject: INFORMATION ON MULTEC FUEL INJECTORS/CLEANING Models Affected: 1986-1991 ALL MODELS WITH PORT FUEL INJECTION Figure 1: 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. (see 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.