The canister on my 88' 900 has an issue. One of the previous owners plugged the vacuum line going into the canister, from the inlet manifold. The fuel fume line is still connected, but the other(to the inlet) is just plugged. If I connect it correctly, the CEL light comes on after idling a few minutes. What might be the problem here? Is it alright just to leave the thing plugged, and have the canister vent out from it's location?