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Troubleshooting Mercury Outboard Battery CD ignitions

********      This information is supplied as a service guide only and 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.      ********

Recommended Tools:
for DVA:  Fluke  Multimeter with CDI #511-9773 Peak Adapter, (or CD-77)
CDI #511-9701 Battery CD Tester
CDI #511-9710 Trigger Tester
CDI #511-9766 Spark Gap Tester
Jumper Wires
A Reliable Volt/Ohm Meter (it the CD-77 is used for the DVA)
CAUTIon; DO NOT Use A FREE Battery with these TypeS of ignitions As theY TEND To OVERCHARGE and BLOW the Packs.> Typically 17 Volts +.
Note: A large portion of the problems with the battery CD units are caused by low battery voltage or bad ground connections or high battery voltage.  Low Voltage symptoms are weak erratic firing of cylinders. Misfiring after a few minutes of running can be caused by excessive (Over 15.5 Volts DC) voltage at the pack. - Warning : Check the voltage on the red (or purple) Wire at the CD Unit through the RPM range. At no time should the voltage exceed 15.5 Volts DC.


1) Check all battery and ground connections.
2) Dead or no fire until you release the key switch:
Disconnect the Mercury Outboard switch and reset, if the engine fires, replace the Mercury Outboard switch. Check the voltage on the red and white Ignition wires at the CD Unit. If the voltage is less than 9 1/2 volts during cranking there is a problem in the battery s or the Ignition switch Box. These units require at least 9 1/2 volts to fire properly. On a 332-2986 switch Box, check the voltage on the brown terminal (white/black for 332-47960 where the Trigger is hooked up. It requires at least 9V at cranking.  DVA check between the white and black wires (black and blue on 332-4796). You should read at least 2 1/2 volts at cranking. Connect a jumper Wire directly from the battery POS (+) terminal to the red and white Ignition wires (the red Wire is not needed for the CDI units). CAUTIon: DO NOT Connect the JUMper Wire To the WHITE Trigger Terminal.  Retest:   ATTENTIon: in order to kill the engine if it cranks, the jumper Wire has to be disconnected and/or choke the engine. If the engine still fails to crank, recheck voltage as above. If low, replace the battery and retry. If there is still no fire, disconnect points Wire (or Trigger wires) and connect the Battery CD tester (511-9701), according to the instructions in the manual, and align the rotor with a spark plug Wire. Connect a spark gap tester (511-9766) to all spark plug wires and turn the Ignition switch on. If the CD Unit fires to only one spark plug Wire, check points Wire (for breaks or shorts) or Trigger. If ANY other spark plug fires besides the one the rotor is aligned with, the distributor cap and rotor should be replaced. The Battery CD tester will fire the system to approximately 3000 RPM. If the Battery CD tester is not used, see related drawings on the Schematic page (following). If the CD Unit fails to fire with this hookup, it is usually bad. Following the instructions included with the Trigger Tester (511-9710) check the Trigger to see if it is good or bad.


3) Engine cranks and fires as long as starter is engaged:
This problem usually indicates a bad Trigger.


4) Check the Ignition coil.
An open, cracked or poorly grounded coil can burn out a battery CD.


5) Check the DVA voltage on the primary input Wire to the coil.
Using the fluke meter with the peak reading voltage adapter (5111-9773), or CD 77. The reading should be approximately 100 volts or more for OEM CD's, and 200+ for CDI electronics units.


6) Inline engines with internal exhaust plate:
If the engine speeds up when you remove one spark plug Wire, the internal exhaust plate is more than likely warped. The following tests can be performed on the bench or on the engine.  NOTE: Disconnect the Trigger mechanism prior to testing.


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