BASIC ELECTRONIC IGNITION TROUBLESHOOTING CHARTS
| NOTE: | Before diagnosing an electronic ignition system, ensure that all wiring is connected properly between distributor, wiring connector and spark plugs. Ignition problem will show up either as: Engine Will Not Start or Engine Runs Rough. |
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Engine Won't Start | ||
| Open circuit between distributor and bulkhead connector | Repair circuit | |
| Open circuit between bulkhead connector and ignition switch | Repair circuit | |
| Open circuit between ignition switch and starter solenoid | Repair circuit | |
| Engine Runs Rough | ||
| Fuel lines leaking or clogged | Tighten fitting, remove restriction | |
| Initial timing incorrect | Reset ignition timing see ENGINE PERFORMANCE | |
| Centrifugal advance malfunction | Repair distributor advance | |
| Defective spark plugs or wiring | Replace plugs or plug wiring | |
| Component Failure | ||
| Spark arc-over on cap, rotor or coil | Replace cap, rotor or or coil | |
| Defective pick-up coil | Replace pick-up coil | |
| Defective ignition coil | Replace ignition coil | |
| Defective vacuum unit | Replace vacuum unit | |
| Defective control module | Replace control module | |
BASIC ELECTRONIC IGNITION TROUBLESHOOTING CHARTS - USING OSCILLOSCOPE PATTERNS
| CONDITION & POSSIBLE CAUSE | CORRECTION | |
|---|---|---|
| Firing Voltage Lines are the Same, but Abnormally High | ||
| Retarded ignition timing | Reset ignition timing, see ENGINE PERFORMANCE section | |
| Fuel mixture too lean | Readjust carburetor, see ENGINE PERFORMANCE | |
| High resistance in coil wire | Replace coil wire | |
| Corrosion in coil tower terminal | Clean and/or replace coil | |
| Corrosion in distributor coil terminal | Clean and/or replace distributor cap | |
| Firing Voltage Lines are the Same but Abnormally Low | ||
| Fuel mixture too rich | Readjust carburetor, see ENGINE PERFORMANCE | |
| Breaks in coil wire causing arcing | Replace coil wire | |
| Cracked coil tower causing arcing | Replace coil | |
| Low coil output | Replace coil | |
| Low engine compression | Determine cause and repair | |
| One or More, But Not All Firing Voltage Lines are Higher Than Others | ||
| Carburetor idle mixture not balanced | Readjust carburetor, see ENGINE PERFORMANCE | |
| EGR valve stuck open | Clean and/or replace valve | |
| High resistance in spark plug wires | Replace spark plug wires | |
| Cracked or broken spark plug insulator | Replace spark plugs | |
| Intake vacuum leak | Repair leak | |
| Defective spark plugs | Replace spark plugs | |
| Corroded spark plug terminals | Replace spark plugs | |
| One or More, But Not All Firing Voltage Lines Are Lower Than Others | ||
| Curb idle mixture not balanced | Readjust carburetor, see ENGINE PERFORMANCE | |
| Breaks in plug wires | Replace plug wires causing arcing | |
| Cracked coil tower causing arcing | Replace coil | |
| Low compression | Determine cause and repair | |
| Defective spark plugs | Replace spark plugs | |
| Corroded spark plugs | Replace spark plugs | |
| Cylinders Not Firing | ||
| Cracked distributor cap terminals | Replace distributor cap | |
| Shorted spark plug wire | Determine cause and repair | |
| Mechanical problem in engine | Determine cause and repair | |
| Defective spark plugs | Replace spark plugs | |
| Spark plugs fouled | Replace spark plugs | |
