Diagnostic Strategies

When checking engine trouble, it is important to start with an inspection of the basic Systems. If one of the following conditions exists, (A) engine start failure, (B) unstable idling or (C) poor acceleration, begin by checking the following basic systems.

1. Power supply
- Battery
- Fusible link
- Fuse

2. ECM ground

3. Fuel supply
- Fuel line
- Fuel filter
- Fuel pump

4. Ignition system
- Spark plug
- High-tension cable
- Ignition coil
- ECM

5. Emission control system
- PCV system
- Vacuum leak

6. Others
- Ignition timing
- Idle speed

Trouble with the MFI system is often caused by poor contact of the harness connectors. It is important to check all harness connectors and verify that they are securely connected.