TESTING PROCEDURE FOR REMOTE CANISTER CONTROL VALVE. GMC Truck Caballero 1983

For 1990-2009 cars

# TESTING PROCEDURE FOR REMOTE CANISTER CONTROL VALVE

#### MODELS: 1982-1984 CABALLEROS WITH 3.8L (VIN CODE A) BUICK BUILT ENGINES

Should a vehicle be received with comments of low fuel mileage, poor performance, or a check engine light on with Code 45, the canister purge valve should be checked per the procedures provided in this bulletin.

When diagnosing a condition such as rough idle, rich acceleration, or lean idle duty cycles (high dwell readings indicate an over rich condition), the following procedure should be followed for diagnosis of the canister control valve:

1. Apply a short length of 3/8" (9.5 mm) I.D. hose to the valve's carburetor bowl tube on the canister control valve (#7 in figure) and blow very lightly into it. Air should pass out through both the canister tube and purge valve tube (#4 and #6 in figure). If it does not, replace the canister control valve.

2. Use a hand vacuum pump to apply vacuum (15" Hg or 51 kPa) to the manifold vacuum tube (#1 in figure). The diaphragm should hold vacuum for at least 20 seconds. If it does not, replace the canister control valve.

3. With vacuum still applied to the manifold vacuum tube (#1 in figure), again try blowing lightly through the hose into the carburetor bowl tube (#7 in figure). No air should flow from the canister tube or purge vacuum tube (#4 and #6 in figure). If air does pass through either tube (#4 and #6 in figure), the valve assembly is not sealing properly, and the canister control valve must be replaced.

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.