GM Full-Size Trucks 1970-1979 Repair Guide

Evaporative Canister



See Figure 1

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Fig. Fig. 1: Cross-sectional view of an evaporative canister

The only regular maintenance that need be performed on the evaporative emission canister is to regularly change the filter and check the condition of the hoses. If any hoses need replacement, use only hoses which are marked EVAP . No other types 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. The filter should be replaced according to the scheduled maintenance.

  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 bottom of the canister.
  5. Pull the filter out and throw it away.
  7. Install a new canister filter.
  9. Install the bottom of the canister and tighten the clamps.
  11. Check the hoses for cracks, restrictions or hose connection openings.