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Introduction
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******** This information
is supplied as a service guide only and Outboardparts.com is not
liable for any misunderstandings, errors or omissions regarding
this information. The information has been obtained from actual
Unit analysis, parts manuals, and other
sources. ********
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| The purpose of this brochure is to give the
marine technician a general overview or the types of test
equipment and their use. The most common, easy to use, test
equipment will be covered. |
| Due to the rapid development of computerized EFI
(Electronic Fuel Injection) and ECU Ignition systems, more
complicated and expensive test equipment will be developed for
the marine industry, just as it has been developed for the
automotive industry. Some newer equipment will include the use of
scope meters (such as the Fluke 98), ECU and EFI testers, digital
analyzers, and computer interface testers. Hopefully, the newer
test equipment will be user friendly and many Troubleshooting
problems will be diagnosed with less complicated equipment. |
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| The test procedures at the end of this brochure
are intended to give the technician a better understanding of the
most common failures and allow testing with minimal
equipment. |
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Test Equipment and
Measurements
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| I. VOM (Volt-Ohm-Meter)
Multimeter |
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A. Analog
meter - The analog VOM is a
dial/needle movement with multiple switch settings
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and ranges on each setting. This meter usually
requires"calibrating" of the scale before use. |
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normally consume batteries at a fast rate. |
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| B. Digital
meter - The digital VOM uses a
digital display to indicate the readings. Of the |
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following types, the manual and autoranging are the most
popular: |
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1. Manual range setting
- The measurement range is
selected by a switch, i.e. 20 ohm, |
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200 ohm, 2k ohm, 200k ohm and 20M ohm. The symbol for ohms
is W. |
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2. Autoranging
- A true autoranging meter will automatically
select the correct range for |
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the measurement being taken, i.e., you can measure 20 ohms and 2k
ohms without |
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changing anything on the meter. The Type of measurement
still has to be manually |
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selected, i.e., AC Volts, DC Volts, Ohms, AC Amps and DC
Amps. |
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3. Manual / Autoranging
- Some meters have both manual
and automatic settings, i.e., |
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the Fluke 88, Fluke 29, etc. |
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4. Ranges - As a reminder, when referring to electronics, the k is
1000, i.e., 1k ohm is |
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1000 ohms and 20k ohms is 20,000 ohms. The M is 1,000,000
i.e., 2M ohm is |
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2,000,000 ohms. |
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| II. Peak Reading
Voltage Measurement |
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A. DVA (Peak Reading)
Voltmeters - Specialty meters
for measuring average DC |
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voltages and AC voltage spikes on Ignition systems. Some of the
more common |
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meters include the Stevens CD-77, Merc-o-tronic and ESI meters
with DVA ranges. |
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B. Multi-use Voltmeters with DVA
Adapters - Analog or digital VOM
(volt, ohm |
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meters) using a plug-in DVA adapter to measure DVA voltages.
Accuracy varies |
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quite a bit between manufacturers and types of meters when taking
DVA readings. |
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The CDI/Rapair 511-9773 peak adapter is highly recommended for
use with all |
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Fluke meters. |
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| III. RPM (Tachometer)
Measurements |
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A. Inductive Tach
Measurements - This type
measurement is made by clamping a |
| inductive pickup probe on one of the
spark plug wires. Very few of the inductive systems will work
well on two cycle CD ignitions due to the RF and microwave noise
being generated. The Fluke 88 Multimeter used with the CDI/Rapair
511-9788B two cycle adapter, is highly recommended.
The Merc-o-Tronic Inductive Tach and the CDI/Rapair
Tach Adapter (P/N 511-9785) are some of the units recommended for
both two and four cycle service. Inductive tachometers can
be a real time-saver when trying to find a high speed miss by
comparing the readings on all cylinders, i.e., if one or two
cylinders shows a big difference in comparison to the other
cylinders. The use of inductive tachometers is recommended for
detection of double firing cylinders. If one cylinder shows twice
the RPM of the other cylinders, it is probably double
firing. |
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B. Reflective Tach
Measurements - These are optical
tachometers, that use a piece of |
| reflective tape on the flywheel or pulley. |
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C. Contact Tachometer
- NOT RECOMMENDED for Outboard Use. |
| Uses a center hub rotator and counts the
RPM.. |
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D. Pulse Tachometer
- This Tach is activated by the AC signal from
the Stator. The |
| RPM signal is related to the number of Pulses
received from the Stator. |
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| IV. Temperature
Measurements |
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A. Thermocouple / Meter
System - This is probably one of
the most useful systems. |
| The Fluke 51 and 52 temperature meters, or the
accessory temperature attachments for the Fluke meters, are
capable of measuring exhaust gas temperature, water temperature,
head and block temperature. Various probes are available for
different types of measurement with the bead probe being one of
the most useful. The bead probe can be positioned on the block
with the use of duct tape. |
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B. Infrared Temperature Probes - They can be used to measure
temperature at various |
| points on the engine or water temperature
without contact. However, some running engines generate too much
electronic static and will interfere with the infrared sensor
readings. Holding the temperature probe too close may cause
the Ignition noise to ruin the Unit. |
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C. Temperature Sticks, Paint or Labels - These can be used for
quick measurement |
| of over heating conditions. |
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| V. Pulse Measurements /
Frequency Measurements |
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| This is a good method to check electronic fuel
injection systems (EFI). A measurement of the injector Pulses at
a set RPM can determine if the injection system is performing
properly. At the current time there are few recorded
measurements on the various EFI systems. The Fluke 88 meter is
one of the meters designed to measure EFI Pulse
rates. |
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| VI. Resistance
Measurements |
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| This is one of the first and easiest
measurements that needs to be taken on an Ignition
system. The charts in the back of this brochure are
furnished as a guide. Be aware that temperature can make a
slight difference in the readings. The higher the temperature -
the higher the resistance reading is going to be. One final note,
a Stator or Trigger can test fine with an ohmmeter and still be
bad. |
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| VII. Current
Measurements |
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A. Direct Volt Amps (DVA)
- One of the most important
measurements to be taken on |
| Ignition systems are voltage measurements using
a DVA meter, or peak reading (DVA) adapter with a good VOM. The
Fluke *a Kit is highly recommended by out Technical Service
Department. The charts in the back of this brochure give the
readings for a majority of the engines. On an engine with a split
Ignition, if only one side fires, compare the readings between
the sides. Typically, the DVA readings for Yamaha and Suzuki will
be close to that of Mercury Outboard. A simple test on
rectifier/regulators (except OMC rectifier/regulators without
cooling fins on the bottom) can sometimes be a time-saver. with
the engine running at approximately 1200-1500 RPM. DVA test from
each yellow Wire to engine ground. The readings should be within
11/2 volts of each other, i.e., if one Wire reads 20 volts - the
other has to read between 18 1/2 and 21 1/2 volts. If one
Wire reads low, mark the Stator and rectifier Wire with the low
reading, shut the engine down and swap Stator wires. Crank the
engine up and repeat the test. Whichever part with the striped
Wire that has the low reading is bad. Repeat the test for yellow
wires to the red Wire going to the battery /
solenoid. |
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B. DC Voltage
- Most battery CD Ignition modules are sensitive
to low battery voltage |
| and battery reversal. During cranking, a DC
voltage level at the pack of less than 9 !/2 Volts is
unacceptable and indicates a problem in the Harness, keyswitch,
starter or battery. WOT voltages above 16 volts will blow most
battery ignitions. Problem is likely to be either the battery or
cables. |
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| VIII. Current
Measurements |
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| This is a good way to check the
regulator/rectifier battery charging operation in the charging
system. The 10 amp charging system can be checked with a good VOM
that has up to 10 amp capability (Fluke 29,73,88, etc.). The red
Wire is disconnected from the rectifier, the one meter probe is
placed on the connection, and the other is placed on the red
Wire. |
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| Warning! Make sure you do
not exceed 10 amps or touch ground with one
probe. This could damage the meter. The 35
amp charging system requires an inductive pick up or a high
current amp adapter, such as CD/Rapair's 511-9772 (1-400
amp). Remember, on outboard charging systems at idle speed the
current is @ 1/5 of the current rated. |
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| IX. Battery CD
Tester |
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| This is used to test battery CD modules on the
engine by replacing the points or triggering device
electronically. The CDI 511-9701 Battery CD Tester is highly
recommended due to its ability to fire the Ignition systems up to
3000 RPM without the engine running. It can be used to test the
CD module, distributor cap, Ignition coil and plug wires.
Additionally, the tester can be used to test Mercury Outboard EFI
injectors. |
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| X. EFI
Tester |
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| Electronic fuel injection testers are available
for use with the specific type of EFI system it was designed for.
Use of these testers are not covered in this brochure. |
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| XI. Trigger
Tester |
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| A break through by CDI/RAPAIR (511-9710) allows
you to test most Mercury Outboard, Mariner, Chrysler triggers and
OMC's Quick Start timer bases on the engine. The Unit can be
used to test points, preamp triggers, Mercury Outboard battery CD
triggers, hall effect triggers, Alternator driven Ignition
triggers, and can be used to check injection Pulse from Mercury
Outboard EFI modules. |
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