NS-13A: Performing No Fault Code Mechanical Test

At this point in the start and stall test procedure, you have determined that all of the engine control systems are operating properly. The engine control systems are NOT the cause of the start and stall problem.

The following items should be checked as possible causes:

• ENGINE VACUUM must be at least 13 in. Hg in Neutral.
• ENGINE VALVE TIMING must be within specification.
• ENGINE COMPRESSION must be within specification.
• EXHAUST SYSTEM must be free of restrictions.
• PCV SYSTEM must allow crankcase gases to flow freely.
• ENGINE CAMSHAFT & CRANKSHAFT SPROCKETS must be in good mechanical condition.
• TORQUE CONVERTER STALL SPEED must be within specifications.
• FUEL CONTAMINATION: Fuel should NOT have a high alcohol or water content.
• TECHNICAL SERVICE BULLETINS should be checked for possible solution to problem.
• SECONDARY IGNITION CHECK: Use an engine analyzer and check for abnormal scope pattern(s).

Any one or more of these items can give a start and stall related problem. They cannot be overlooked as possible causes.