GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Evaporative Canister


See Figures 1 and 2

The evaporative canister, sometimes referred to as a charcoal canister, is mounted inside the engine compartment. The canister and its filter are part of the evaporative emissions system (see Driveability & Emissions Controls ) and work to eliminate the release of unburned fuel vapor into the atmosphere. The vapor is absorbed by the carbon in the canister and stored until manifold vacuum, when the engine is running, draws the vapors into the engine for burning.

The filter in the bottom of canisters with open bottoms must be changed every two years or 24,000 miles, or more often under extremely dusty or smoggy conditions.


  1. Tag and disconnect all hoses connected to the evaporative canister.
  3. Loosen the retaining clamps and then lift out the canister.
  5. Grasp the filter element in the bottom of the canister with your fingers and pull it out. Replace it with a new element.
  7. Replace the canister in the clamps and reconnect all hoses. If any of the hoses are brittle or cracked, replace them only with fuel-resistant replacement hose marked EVAP.

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Fig. Fig. 1: Fuel evaporation canister.

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Fig. Fig. 2: Common fuel evaporation canister location