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FUEL INJECTION SYSTEM TROUBLESHOOTING
Important Preliminary Checks
BEFORE STARTING
Before using this section you should have performed the "On-Board Diagnostic (OBD) Sys-
tem Check" in in the "General System Diagnostics" section and determined that:
The ECM and/or MIL (Malfunction Indicator Lamp) are operating correctly.
There are no DTC(s) stored.
Verify the customer complaint and locate the correct symptom in the table of contents.
Check the items indicated under that symptom.
Visual/Physical Check
Several of the symptom procedures call for a careful Visual/ Physical Check. The impor-
tance of this step cannot be stressed too strongly. It can lead to correcting a problem without
further checks and can save valuable time. This check should include:
ECM grounds and sensor connections for being clean, tight and in their proper location.
Vacuum hoses for splits, kinks and proper connections. Check thoroughly for any type of
leak or restriction.
Air leaks at throttle body mounting area and intake manifold sealing surfaces.
Ignition wires for cracking, hardness, proper routing and carbon tracking.
Wiring for proper connections, pinches and cuts. If wiring harness or connector repair is
necessary, refer to "Description and System Operation" section for correct procedure.
Moisture in primary or secondary ignition circuit connections.
Salt corrosion on electrical connections and exposed throttle body linkages.
INTERMITTENTS
IMPORTANT: Problem may or may not turn ON the Malfunction Indicator Lamp (MIL)
or store a DTC. DO NOT use the Diagnostic Trouble Code (DTC) tables for intermittent
problems. The fault must be present to locate the problem.
Most intermittent problems are caused by faulty electrical connections or wiring. Perform
careful visual/physical check. Check for the following conditions:
Poor mating of the connector halves, or a terminal not fully seated in the connector body
(backed out or loose).
Improperly formed or damaged terminals and/or connectors.
All connector terminals in the problem circuit should be carefully checked for proper contact
tension.
Poor terminal to wire connection (crimping). This requires removing the terminal from
the connector body to check. Refer to "Wiring Harness Service" in the "Description and
System Operation" section.
The vessel may be driven with a Digital Multimeter connected to a suspected circuit. An
abnormal voltage when malfunction occurs is a good indication that there is a fault in the
circuit being monitored.
Index
Page 5D-6
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SERVICE MANUAL NUMBER 23
90-861326--1 MARCH 1999
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