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| The alternator comes in several varieties depending on which
year C4 you have. Corvettes have a history of problems with
the alternator and electrical system faults can frequently be
traced to this device. |
| In 1984, the alternator output amperage was 97 amps maximum
load. In 1985, this was increased to 120 amps and there
were three different models of alternator with GM P/N 1049868
being the number for all of them. If you replace the alternator
with a GM unit, you will get the final version. |
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In 1986, the amperage was dropped back to 105
amps where it remained.
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| To determine if alternator is working, start the engine and
turn on all accessories...radio, all lights, air conditioner...everything.
Select volts on the function select switch panel. Observe
engine RPMs and with your foot securely on the brake, place the
automobile in gear and out of gear several times. (For a manual
transmission, you will have to lightly load the engine but not
to the point where is begins to stall, depress the clutch then
load it again several times). |
| Observe the voltage display and if the indicator is less than
11.5 volts, either the alternator or battery (or possibly both)
may be defective. |
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| The ignition system on the 1984-1991 C4 L98 engine Corvette
has the ignition coil housed in the distributor cap on the rear
of the engine which is connected via a brush arrangement to the
rotor. (Later models use the so called Opti-Spark system which
has an optical isolator driven distributor and is prone to ingestion
of water. This water contamination will prevent operation unless
a special kit is installed to eliminate the moisture or unless
your C4 is a later model which had the kit installed by the factory.
Repair of the Opti-Spark system is difficult and best left to
the pros. If you wash the engine of a later model (LT1 or
later) C4 and it will then not start or starts but will hardly
run, you have probably caused the Opti-Spark to ingest water and
are looking at a large repair bill). |
| If the engine turns over but will not start, you should check
for a spark before checking for sufficient fuel flow and pressure.
(You should of course first verify that there is fuel in the tank
via reference to the fuel gauge). Note that this troubleshooting
order is not because the ignition system is more likely to fail
than the fuel system but rather because it is somewhat easier
to check and should be eliminated for that reason before moving
on to the fuel system. |
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