LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1990 >> Forward Control 3.9 L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Diagnostic Procedure >> Preliminary Inspection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Preliminary Inspection

  1. Check all vacuum hoses for correct routing, restrictions, cuts, or other damage. Inspect hoses see beneath the air cleaner assembly and other engine components.
  2. Inspect all wires in engine compartment for correct and good connections. Also check wires for pinched or chaffed spots, as well as contact with sharp edges or exhaust manifolds.
  3. The preliminary inspection is very important and should be performed CAREFULLY and THOROUGHLY as it can often lead to fixing a problem without further diagnosis.
scientia non olet · About LEMON Manuals