Diagnostic Aids

If no trouble is found in fuel pump circuit or ignition system and the cause of a "Engine Cranks But Will Not Run" has not been found, check for the following:

• Fouled spark plugs.
• EGR valve stuck open.
• Low fuel pressure. See CHART A-6.
• Water or foreign material in the fuel system.
• A ground circuit 423 (EST) may cause a "No Start" or a "Start then Stall" condition.
• Basic engine problem.

Fig 1: Chart A-3 Schematic, Engine Cranks But Will Not Run (2.8L (S & T Series), 4.3L & V8 (P, G, G/P, R & V Series))

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart A-3 Schematic, Engine Cranks But Will Not Run (4.3L & V8 (C, K & M Series))

Courtesy of GENERAL MOTORS CORP.

Fig 3: Flow Chart A-3, Eng. Cranks But Will Not Run (All But 2.5L)

Courtesy of GENERAL MOTORS CORP.