Troubleshooting Tests - Mercury MerCruiser MCM 454 Mag MPI Service Manual

CHARGING SYSTEM
5. While holding adjustment stud at the correct belt tension, tighten 5/8 in. locking nut.
7.4L MPI Shown - All Others Similar
6. Operate the engine for a short period of time. Recheck belt adjustment.
7. If a new drive belt has been installed, recheck belt tension after running for five minutes.
Troubleshooting Tests (Alternator on Engine)
Use the following tests in conjunction with "Troubleshooting" in SECTION 1. Before
proceeding with the tests, however, perform the following checks to eliminate possible
problem areas. Also observe "Precautions," preceding, to prevent damage to alternator
system.
1. If problem is an undercharged battery, check to ensure that undercharged condition has
not been caused by excessive accessory current draw or by accessories which have
been left on accidentally. Also, check that undercharged condition has not been caused
by running engine at too low a speed for extended periods of time.
2. Check physical condition and state of charge of battery, as outlined in "Battery - Storage"
in SECTION 4A. Battery MUST BE at least 75% (1.230 specific gravity) of fully charged
to obtain valid results in the following tests. If not, charge battery before testing system.
3. Inspect entire alternator system wiring for defects. Check all connections for tightness
and cleanliness, particularly battery cable clamps and battery terminals.
4. Check alternator drive belt for excessive wear, cracks, fraying and glazed surfaces and
replace if necessary. Also, check drive belt tension and adjust if necessary, as outlined
under "Drive Belt Tension Adjustment," preceding.
Index
Page 4C-8
Downloaded from https://needmanual.com/
75509
a - Adjustment Stud
b - Locking Nut
c - Alternator
d - Power Steering Pump on Sterndrive Models
c
d
a
b
75483
SERVICE MANUAL NUMBER 23
75545
90-861326--1 MARCH 1999