Testing Thunderbolt IV HEI System
!
WARNING
IMPORTANT: Use a voltmeter when mak-
ing these tests. DO NOT use a test light.
Be sure that engine compartment is well venti-
lated and that there are no gasoline vapors pres-
ent during the following test to prevent a poten-
tial fire hazard.
Check all Terminal Connections
at Distributor, Ignition Module
and Ignition Coil
Replace
Ignition
Module
Battery OK?
Distributor Clamping Screw
Tight?
0
Volts
No Spark
Check Engine
and Instrument
Wiring Harness,
Battery Cables,
Key Switch
Replace Ignition
Module Harness
With Key in RUN Position,
Check for 12 Volts at Positive
0
Volts
(+) Terminal on Ignition Coil
0
Volts
12
Volts
Unplug WHT/
RED bullet con-
nector from Dist.
Term., then
Check for Voltage
on This Lead
Check for 1-12 Volts at WHT/
RED Terminal on Distributor
0
Volts
1 to 12 Volts
Voltage
Remove High-Tension Lead
from Distributor to Coil. Insert
a Spark Gap Tester from Coil
Tower to Ground. Remove
WHT/GRN Lead from Distribu-
tor Terminal - Ignition Key in
RUN Position. Strike the Termi-
nal on the WHT/GRN Lead
against Ground
Replace Ignition
Sensor in
Distributor
Replace Ignition
Sensor in
Distributor
Spark
at Coil
No Spark at Coil
Substitute a New Ignition Coil.
Repeat Above Test
Spark
at Coil
Install New
Ignition Coil
No Spark at Coil
Replace Ignition Module
Note 1 : Early , large ignition modules did not have a replaceable wiring harness.
Index
1C-8 - TROUBLESHOOTING
90-823224--2 796
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
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