[kaspar]

1st. Make sure battery is fully charged as it does not spin 300rpm or fast it will not fire.
2nd. Remove spark plugs as a dragging starter/defective battery cell will drop rpm and without plugs engine will spin faster.
3rd. Disconnect rectifier and retest as it can cause stator to overheat and fail.
4th .. Was battery dead when you jumped it? That stator is only a 10amp output and really not designed to charge a dead battery. If it was dead or has a bad cell it could cause stator to overheat and melt windings. Look under flywheel and see it there is a gooey epoxy substance oozing from stator windings.

[fergalish]

If you are going to work on this mtr yourself you should get an OMC factory service manual. Lots of info in it on trouble shooting.

[Narcisco88]

Re: Will a rectifier /regulator cause no spark on all 4 cyl? here

[Margaret Stukel]

take ALL the plugs out. and check each plug wire with the tester to see if you are getting spark TO THE PLUG. if you do, then you have a weak starter motor maybe.. [links]

[s20-10s]

Look-up the correct Trigger for your Mercury Outboard by using the PARTS CATALOG link below.
It is best to enter your engine serial number for accurate results.
Copy down your trigger part number and email us with your request.
Please include your trigger part number and your engine serial number!

[jhoki]

Your outboard trigger tells the switchbox when to "fire".
The inner ring of your flywheel has magnets which pass close to the triggers coils.
Each time the magnet passes, the trigger sends a low voltage "signal" to the switchbox.

[harrison801]

Triggers are very reliable
Triggers can fail for one or more of the following reasons.
1. Age! Old triggers fail from internal failures from temperature fluctuations and/or corrosion.
2. The wire insulation gets old and crumbles off.
here

[destinbrides]

A faulty or failing trigger can cause one or more symptoms.
1. Engine fails to run and has no spark (possibly on only one cylinder).
2. Engine is hard to start especially after sitting from a run.
3. Engine is low on power or has a "miss".
4. Engine stalls frequently.
[links]

[horseracing12]

With no external signal to the coil negative primary post, voltage would travel through the ignition coil windings without inducing any secondary spark. A switch, or signaling device, triggers an interruption in the circuit. High voltage is then generated in the coil windings. Voltage transformation produced by the interruption coincides to each spark generated. Older ignition systems used breaker points to interrupt the circuit, while more modern systems "sense" the need for spark by means of a hall-effect switch or crankshaft position sensor. The ignition module uses the information to time spark generation. Test these components if the energized coil fails to function. here

[pj]

Normally, the high secondary voltage produced by an ignition coil is quite powerful. You can replace the secondary coil wire on an engine that uses one with an equal length of vacuum hose and the engine will start and run. The powerful spark will travel down the hollow hose to the distributor cap, but the engine will stall under any load because of the weakened spark. However, the coil will not fire across a wide gap or through thick corrosion. Ensure secondary spark conductors are complete circuits with good connections and insulation to gain successful voltage delivery.

[Kiv]

Two positions of the ignition switch provide power to the positive primary post of the ignition coil. In the "start" position, the switch energizes the starter motor, and full battery voltage is directed to the coil while the engine cranks. Once the engine starts, the switch is released to the "run" position. The coil still receives voltage, but the amount may be reduced by a resistor in the "run" circuit. In either instance the supplied voltage must be continuous. Examine the battery, ignition switch and circuitry if the coil primary voltage is errant or not present at all. [links]

[reverselockup23]

Certain requirements must be met for an ignition coil to produce the high-voltage spark that fires an engine. Problems associated with meeting these requirements can be as simple as a corroded wire or weak battery. More complicated issues may also contribute to spark loss, but basic conditions are still the general means for good function of any ignition system. Knowing what to look for when troubleshooting ignition systems can allow proper decisions to be made when selecting repair procedures or replacement parts.

[MH80]

Any break in a conductive material, like a wire, creates an open circuit. An open circuit behaves as though it were switched off. The windings in an ignition coil are no more than thin wires, and open circuits can occur inside the coil. You can test the continuity of coil windings by measuring the resistance with an ohmmeter. Corroded connections can have enough resistance to essentially create an open circuit. Bad ground connections have the same effect as any open circuit, and battery and engine grounds should not be overlooked when diagnosing a "no spark" condition.

[zipslack]

Admittedly don’t have a manual close by, but remember the long/sensitive process. This part is so sensitive that I’m pretty sure the manual mentions different resistance readings that might be found on a few different brand ohm meters…I believe the term “impedence” was tossed around also. Were you using a peak reading voltmeter when checking the voltage output? If so, was it set to the proper scale? I won’t be home for a week or so, perhaps Dan can review the sensor troubleshooting procedures with you. In any event, the sensor works in two modes, quikstart and run. There are several tests to check output/resistance in both modes.
In any event, the sensor would not be my “first bet” in a no spark situation, unless you found damaged/burned/melted leads. Did you do the key switch elimination test? Did you check the pack and coil ground connections with an ohm meter on the low scale? Those amphenol connections can be troublesome also, did you check each black plug to make sure none of the pins/sockets were bent or partially pushed out? Please don’t be offended if I ask if the emergency stop lanyard is properly attached to the control or switch on the dash….Happens to the best of us.
Have you checked the powerpack charge coil resistance and output? If so, did you use a peak reading voltmeter? There is a “power coil” that provides power for the quikstart/SLOW systems also, but I’m pretty sure the engine will still spark even if the power coil is bad.
Please know that I am not trying to question your troubleshooting methods/results, but the sensors would not be my first guess. I would surely want to eliminate all other simpler causes before replacing the sensor assy. Again, this part is very expensive, and most dealers would not offer a refund once it has been installed.
When was the last time this engine had spark, what has changed since then? Is the battery fully charged? Low cranking speed can cause no spark due to low charge coil/sensor output.
Don [links]

[diggler]

Not only is this part delicate/sensitive, but it is also expensive…..Why is it that you are replacing the sensor assembly? I just don’t want you to spend time/money replacing something that might not be busted…..

[fergalish]

Followed the service manual troubleshooting directions for no spark on any cylinder. Everything was as expected until I came to the sensor coil. At that point I had .06 v instead of the required .3 v between pin D and pins A,B and C. Then the resistance checks were: D to E=446 ohms, D to A,B,C was measuring open on any scale. Since I was not getting the results the shop manual indicated, I figured the sensor coil was defunct. Couldn’t see continuing when I had results that were not what the manual called for. I’m open to suggestions that indicate I’m missing something. Not looking to spend money chasing an incorrect diagnosis. more

[Cryptoman]

I’ll give it a shot. I see your listed as Canadien member, are you up there? We visit my cousins in Cape Breton in the fall.