FUEL INJECTION SYSTEM TROUBLESHOOTING
SERVICE MANUAL NUMBER 24
Page 5F-18
90-861327--1 OCTOBER 1999
Rough, Unstable, or Incorrect Idle, Stalling Symptom
(Continued)
Step
Action
Yes
No
PROCEED TO
9
1. Disconnect all injector harness connectors
and install an injector test light J 34730-2
between the harness terminal connector of
each injector.
2. Crank engine and note light on each con-
nector. If test light fails to blink at any one of
the connectors, it is a faulty injector drive
circuit harness, connector or terminal.
Was a problem found?
Step 10
10
1. Check fuel injectors.
•
Refer to Injector Balance Test in “General
System Diagnostics” section.
Was a problem found?
Step 11
11
1. Check for fuel in pressure regulator vac-
uum hose.
2. If fuel is present, replace the fuel pressure
regulator assembly.
•
Refer to Fuel Metering System in “De-
scription and System Operation” section.
Was a problem found?
Step 12
12
1. Check for intermittent opens or short to
grounds in the ECT sensor, MAP sensor
and TP sensor circuits. Also check or
throttle linkage sticking, binding or worn.
2. An intermittent failure may not store a DTC.
Was a problem found?
Step 13
13
1. Check ECM grounds for being clean, tight
and in their proper locations.
2. Also check that battery cables and ground
straps are clean nd secure.
Were ECM grounds dirty, loose or
improperly connected?
Step 14
14
1. Check fuel delivery system items that can
cause the engine to run rich.
Was a problem found?
Step 15
15
1. Check fuel delivery system items that can
cause the engine to run lean.
Was a problem found?
OBD
Step 16
Index