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  Mercury Mariner Outboard Ignition Troubleshooting Tips

Battery Ignitions
A large portion of the problems with the battery CD units are caused by low battery voltage and/or bad ground connections. Low voltage symptoms are weak fire or weak erratic firing of cylinders.
1) Check all battery and ground connections.
2) Dead or no fire until you let off of key switch: Check the voltage on the red and white ignition wires at the CD unit. If the voltage is less than 9.5 volts at cranking, there is a problem in the battery wires or ignition switch circuit. these units require at least 9.5 volts to fire properly. On a 332-2986 switch box, check the voltage on the brown terminal(white/black for 332-4796) where the trigger is connected. It requires at least 9 volts at cranking. DVA check between the white and black wire(black and blue on 332-4796). You should read at least 2.5 volts at cranking. Connect a jumper wire directly from the battery(+) terminal to the red and white ignition wires. 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 battery and retry. If there is still no fire, disconnect points wire(or trigger wires) and connect to battery CD tester according to the instructions on the back of the tester, and aline rotor with a spark plug wire. Connect a spark gap tester to all plug wires and turn the ignition switch on. If the CD unti fires to only one spark plug wire, check points wire(for breaks or shorts) or trigger. IF ANY other plug wires fire besides the one that the rotor is aligned with, the distributor cap and rotor should be replaced. The battery CD tester will fire the system to approximately 3,000 RPM. If the battery CD tester is not used, strike points wire against engine ground. If the CD unit fails to fire with this hookup, the CD unit is usually bad.
3) Engine cranks and fires as long as the 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, or CD-77. The reading should be approximately 100 volts or more for OEM CD's.
6) Inline engines with internal exhaust plate: if engine speeds up when you remove one spark plug wire, the internal exhaust plate is more than likely warped.


Power Packs and CD's

1) Disconnect the kill wire(s): Connect a DC voltmeter between the kill wires and engine ground. Turn ignition switch on and off several times. If at any time you see DC voltage appearing on the meter, there is a problem in the harness, or ignition switch. Note: At no time should you see voltage on any kill wires. Battery voltage on the kill circuit will destroy most CD units.
2) Visually inspect stator for cracks or leaks: if found, replace the stator. Burnt 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 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 the two blue wires), with everything connected. The readings should be approximately 180 volts or more on the blue wires, and 30 volts or more on the red wires. Disconnect the rectifier. If the engine fires, replace the rectifier.
4) Engine will not kill: Check 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 it to ground. If this kills the engine, the kill circuit in the harness or on the boat is bad, or possibly the ignition switch has a problem.
5) High speed miss: Disconnect the rectifier and retest. If miss is gone, rectifier is usually at fault. If the miss still exsists, check DVA voltage(between the red wires on 4 cylinder, or red wires to engine ground on 3 and 6 cylinders) 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 this miss becomes apparent, the stator is usally 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 recifier, regulator, and retest. If the problem goes away, replace the rectifier and/or regulator.
7) Engine runs rough on top or bottom 2 cylinders(four cylinder engines): Check DVA voltage of the stator between blue wires and 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 number 1 and number 2, compare to resistance between number 3 and number 4. The readings should be approximately 850 - 1250 ohms. For test purposes only swap trigger leads 1 and 3, and 2 and 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 terminals.
8) No fire on one bank(odd or even cylinders on inline 6 cylinder engines): Check DVA voltage of the stator, checking from each red and blue 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 locations 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 at the same time. If the packs loose ground internally or externally, they usually have severe damage to the bias circuit, and have to be replaced as a set.
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 the 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 timing on all individual cylinders. If the timimg varies, replace the packs. On 4 cylinder engines, the bias circuit is internal therefore, the only way to varify proper operation of the bias circuit, is to index the flywheel and check timing on each cylinder. If the timing is off, replace the packs.
 

 
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