GENERAL SYSTEM DIAGNOSTICS SERVICE MANUAL NUMBER 23
Page 5E-74 90-861326--1 MARCH 1999
Chart A-4 (3 of 5): Fuel System Diagnosis
Step Action Value(s) Yes No
1
Was the “On-Board
Diagnostic” (OBD) System
Check performed?
–
Go to
Step
2
Go to
OBD
System Check
2
1. Install fuel pressure
gauge.
2. Ignition “OFF” for 10
seconds.
3. Ignition “ON.” Fuel
pump will run for
about 2 seconds.
4. Note fuel pressure
with pump running.
The pressure may
drop after the pump
stops running, but the
press re should not
drop immediately to 0
psi. System should
hold pressure for at
least 15 to 20
seconds.
Is fuel pressure within
specified value?
34-38 psi
(234-262) kPa
Go to
Step
3
Go to
Step
5
3
Start engine and idle at
normal operating temper-
ature.
Is fuel pressure lower
by the specified value?
3-10 psi
(21-69 kPa)
Refer to
Symptoms
Section
Go to
Step
4
4
With engine still idling,
connect an external
vacuum source to the fuel
pressure regulator and
apply 10 inches of
vacuum.
Is fuel pressure lower
by the specified value?
3-10 psi
(21-69 kPa)
Go to
Step
14
Go to
Step
16
5
Was fuel pressure
present at all?
–
Go to
Step
6
Go to
Table A-5
6
Does the system estab-
lish fuel pressure and
then drop immediately
to 0 psi?
–
Go to
Step
7
Go to
Step
9
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