Mercury MerCruiser MCM 454 Mag MPI Service Manual page 667

GENERAL SYSTEM DIAGNOSTICS
Chart A-4 (3 of 5): Fuel System Diagnosis
Step
1
2
3
4
5
6
Index
Page 5E-74
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Action
Was the "On-Board
Diagnostic" (OBD) System
Check performed?
Install fuel pressure
1.
gauge.
Ignition "OFF" for 10
2.
seconds.
Ignition "ON." Fuel
3.
pump will run for
about 2 seconds.
Note fuel pressure
4.
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
seconds.
Is fuel pressure within
specified value?
Start engine and idle at
normal operating temper-
ature.
Is fuel pressure lower
by the specified value?
With engine still idling,
connect an external
vacuum source to the fuel
pressure regulator and
apply 10 inches
vacuum.
Is fuel pressure lower
by the specified value?
Was fuel pressure
present at all?
Does the system estab-
lish fuel pressure and
then drop immediately
to 0 psi?
Value(s)
–
34-38 psi
(234-262) kPa
20
3-10 psi
(21-69 kPa)
3-10 psi
of
(21-69 kPa)
Go to Step 14
–
–
SERVICE MANUAL NUMBER 23
Yes No
Go to OBD
Go to Step 2
System Check
Go to Step 3 Go to Step 5
Refer to
Symptoms
Go to Step 4
Section
Go to Step 16
Go to Step 6 Go to Table A-5
Go to Step 7 Go to Step 9
90-861326--1 MARCH 1999