Symptom Diagnosis

Symptom checks should not be used unless symptom occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in basic diagnostic tests in BASIC TESTING - 7.4L article and self-diagnostic tests in TESTS W/CODES - 7.4L article were performed before diagnosing a symptom. Symptoms available for diagnosis include:

• Hard Start
• Stalls After Starting
• Hesitation, Sag Or Stumble
• Vehicle Surges Or Chuggles
• Lack Of Power Or Sluggish
• Engine Backfires
• Cuts Out, Misses
• Rough, Unstable Or Incorrect Idle
• Engine Will Not Idle
• Poor Fuel Economy
• Engine Dieseling/Run-On
• Detonation/Spark Knock
• Excessive Exhaust Emissions Or Odors