Test NTC-5: Checking Engine Vacuum

Start engine. Connect a vacuum gauge to a manifold vacuum source. Let engine idle. Vacuum reading may vary according to altitude. Observe vacuum gauge. If vacuum gauge reading is 13-22 in. Hg and steady, test is complete. If vacuum gauge reading is not 13-22 in. Hg and steady, see TEST NTC-4: CHECKING ENGINE MECHANICAL SYSTEMS  .