LOW SPEED TIP-IN/STUMBLE EXCESS CANISTER VAPORS

WHEN A CONDITION OF POOR ENGINE PERFORMANCE ON LIGHT TIP-IN ACCELERATION IS ENCOUNTERED, IT MAY BE CAUSED BY EXCESS CANISTER VAPORS ENTERING THE INDUCTION SYSTEM. THE CONDITION USUALLY OCCURS AT AMBIENT TEMPERATURES ABOVE 90F. THE CONDITION CAN BE IMPROVED WITH THE INSTALLATION OF A VACUUM DELAY VALVE (SERVICE P/N 14020691) IN THE VACUUM HOSE THAT RUNS FROM THE CARBURETOR (PORT "H") TO THE CANISTER CONTROL VALVE (VACUUM) PORT. THE FOLLOWING PROCEDURE AND ATTACHED SKETCHES SHOW THE CORRECT INSTALLATION. THE EXISTING HOSE ATTACHED TO THE CARBURETOR AT PORT "H" SHOULD BE CUT 2 1/2" + 1/8" FROM THE CANISTER CONTROL VALVE. INSTALL VACUUM DELAY WITH THE BLACK END TOWARD CARBURETOR. REMOVE OR SHORTEN REMAINDER OF HOSE, 2 1/2" + 1/2", AND RECONNECT EXISTING HOSE TO CARBURETOR. * ILLUSTRATION *

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.