Visual Inspection

PRELIMINARY INSPECTION / DIAGNOSTIC PREPARATIONS
These diagnostic procedures are designed to find and repair engine performance problems. Follow the three steps shown below.

Do The On-car Diagnostics Work
To determine if on-car diagnostics are operating perform the diagnostic circuit check. This is always the first step when working on TBI. If the on-car diagnostics aren't working or the engine cranks but will not run, the diagnostic circuit check will direct you to Diagnostic Charts / A-Charts.

If the on-car diagnostics are OK check to see if a trouble code is stored. If a trouble code is stored go to the trouble code number in Diagnostic Trouble Code Charts.

Is The Fuel System Controlling Correctly
This is determined in the Diagnostic Circuit Check and doing the Field Service Mode Check. If the fuel system is not controlling correctly, refer to Diagnostic Charts / A-Charts. If the Field Service Mode Check shows that the system is in closed loop and working properly, go to Diagnosis By Symptom. Diagnosis by symptom lists several driveablity symptoms and suggests checks of related components, which can be found in Diagnostic Charts / C-Charts.

VISUAL CHECK
One of the most important checks that must be done before any diagnostic procedure is a careful visual check under the hood. This step often leads to repairing the vehicle without further steps. Inspect all vacuum hoses for pinches, cuts, or disconnects. Be sure to inspect hoses that may not easily be seen, hidden by the alternator, A/C compressor air cleaner etc. Inspect all electrical wires in the same way, for tight connections, burning, chaffing, or pinches.

NOTE: This visual check is very important and must be done thoroughly.