GM Full-Size Trucks 1988-1998 Repair Information

Evaporative Canister



The only regular maintenance that need be performed on the evaporative emission canister is to regularly change the filter (on those 1988-90 models which utilize one; 1991-98 trucks do not have a canister filter) and check the condition of the hoses. If any hoses need replacement, use only hoses which are marked EVAP. No other type should be used. Whenever the vapor vent hose is replaced, the restrictor adjacent to the canister should also be replaced.

The evaporative emission canister is located on the left side of the engine compartment, with a filter located in its bottom (if applicable).

For further information on the evaporative emission system, please refer to Driveability & Emissions Controls


To service the canister filter:
  1. Note the installed positions of the hoses, tagging them as necessary, in case any have to be removed.
  3. Loosen the clamps and remove the canister.
  5. Pull the filter out and throw it away.
  7. Install a new canister filter.
  9. Install the canister and tighten the clamps.
  11. Check the hoses.