Mechanical Inspection: Compression
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer capable of performing a relative compression test. If using engine analyzer, see engine analyzer instruction manual for availability and description of relative compression feature.
WARNING:
Because fuel injectors on many models are triggered by ignition switch during cranking mode, DO NOT
use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine to prevent fire hazard or engine's oiling system contamination.