Troubleshooting - Toyota 4-Runner 1985 Repair Manual

EFI SYSTEM - Troubleshooting
TROUBLESHOOTING
TROUBLESHOOTING HINTS
FI-9
1 . Engine troubles are usually not caused by the EFI system.
When troubleshooting, always first check the condition of
the other systems.
(a) Electronic source
•
Battery
•
Fusible links
•
Fuses
(b)
Fuel supply
•
Fuel leakage
•
Fuel filter
•
Fuel pump
(c) Ignition system
• Spark plug
• High-tension cord
• Distributor
• Igniter and ignition coil
(d) Air intake system
• Vacuum leaks
(e) Emission control system
• EGR system
• PCV system
(f)
Others
• Ignition timing
• Idle speed
• etc.
2. The most frequent cause of problems is simply a bad con-
tact in wiring connectors. So always make sure that con-
nections are secure.
When inspecting the connector, pay particular attention
to the following points:
(a) Check to see that the terminals are not bent.
(b) Check to see that the connector is pushed in complete-
ly and locked.
(c) Check to see that there is no signal change when the
connector is slightly tapped or wiggled.
3. Sufficiently troubleshoot for other causes before replac-
ing the ECU. The ECU is of high quality and it is expensive.