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Troubleshooting Mercury Outboard Alternator Driven Ignition

********      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 analysis, parts manuals, and other sources.      ********
 
Recommended Tools:
for DVA : Fluke Multimeter with CDI #511-9773 Peak Adapter and:
CDI  #5119770 Piercing Probes
CDI #511-9710 Trigger Tester
CDI #511-9766 Spark Gap Tester
Jumper Wire
A Reliable Volt/Ohm Meter (it the CD-77 is used for the DVA)
 
NOTICE: Initial DVA readings should be taken with everything hooked up. 
 
1)  Disconnect the kill Wire(s):
Connect a DC volt meter between the kill wires and engine ground. Turn the Ignition switch in and off several times. If, at any time, you see DC voltage on the kill wires, there is a problem with the Harness of Ignition switch. Battery voltage on the kill circuit will destroy most CD units.
 
2) Visually inspect Stator for cracks or varnish leakage: 
If found, replace the Stator. Burned marks or discolored areas on the battery charge windings indicate a possible problem with the rectifier.
 
3) Unit will not fire:
Disconnect kill Wire AT the Pack. Check for broken or bare wires on the Unit, Stator and Trigger. Check the DVA voltage of the Stator, (on 3 and 6 cylinder models read from each red and blue Wire to engine ground; on 4 cylinder models read between the two red wires and between the two blue wires), with everything connected. The readings should be approximately 180 volts or more on the blue wires. and 30 or more volts on the red wires. Disconnect the rectifier. If the engine fires replace the rectifier.
 
4) Engine will not kill:
Check the kill circuit in the pack by using a jumper Wire connected to the black/yellow terminal or Wire coming out of the pack and shorting to ground. If this kills the engine, the kill circuit in the Harness or on the boat is bad, possibly the Ignition switch.
 
5) High Speed Miss:
Disconnect the rectifier and retest. If the miss is gone, the rectifier is usually at fault. If the miss still exists, check the DVA voltage (between the red wires on 4 cylinder, or red wires to engine ground on 3 &6 cylinder) of the Stator at high speed. NOTICE: Use caution when doing this and do not exceed the rated voltage range of your meter. The readings should show a smooth climb in voltage. If there is a sudden or fast drop in voltage right before the miss becomes apparent, the Stator is usually at fault. If there is no indication of the problem, it could be a small water leak in one or two cylinders.
 
6) Coils fire with spark plugs out but not in:
Check for dragging starter or low battery causing slow cranking speed. DVA test Stator and Trigger. Disconnect rectifier, regulator and retest. If the problem goes away, replace the rectifier and/or regulator.
 
7) Engine runs rough on top or bottom two cylinders (4 cylinder engines): 
Check DVA voltage of the Stator between blue wires and to ground. Readings to ground should be fairly equal. If unequal, swap Stator leads (blue with blue/white, red with red/white) and see if the problem moves with the Stator leads. If it does, replace the Stator. Check Trigger resistance between #1 & #2, compare to resistance between #3 & #4. The readings should be approximately 850 to 1250 ohms for OEM (950 ohms for CDI). for test purposes only, swap the Trigger leads 1 &3, and 2 &4. If the problem moves, replace the Trigger. If it does not move, swap coil primary wires, and replace the pack if the problem remains on the same cylinder.
 
8) No fire on one bank (odd or even cylinders on inline 6 cylinder engines):
Check the DVA voltage of the Stator, checking from each red Wire to engine ground. The readings should be approximately 180 volts or more on the blue wires and 30 or more on the red wires. if a DVA meter is not available, swap both sets of the Stator wires between the packs. If the problem moves, replace the Stator. If the problem stays on the same bank, swap physical location and all connections of the two packs. If the problem stays with one pack, replace the pack. NOTE: If the pack is bad, it is recommended that BOTH packs be replaced if the packs are not manufactured by CDI or Rapair. If the packs lose ground, internally or externally, the packs manufactured by other sources usually have severe damage to the bias circuit and need to be replaced as a set. The packs manufactured by CDI will withstand loss of ground connection, normally with no damage to the bias circuitry. In most cases you will just lose fire.
 
9) Intermittent firing on one or more cylinders:  
Disconnect the white/black Wire between the packs on a 6 cylinder and retest. If all cylinders now fire, replace both packs as there is a problem in the bias circuitry. On all others, check for low voltage from the Stator and Trigger. Disconnect the rectifier and retest. If the problem disappears, replace the rectifier.
 
10) all cylinders fire but the engine will not crank and run: 
On 3 and 6 cylinder engines, disconnect white/black Wire and check the bias circuit (white/black terminals) resistance to engine ground. Readings should be approximately 15,000 Ohms for Standard packs and 9,600 Ohms for racing units. If the readings are correct on the packs, index the flywheel and check the timing on all individual cylinders. If the timing varies, replace the pack. On 4 cylinder engines the bias circuit is internal, therefore the only way to verify proper operation of the bias circuit is to index the flywheel and check the timing on each cylinder. If the timing is off, replace the packs.

 

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