1989 Mercury Blackmax 150 no spark

[CharlieB]

Re: 1989 Mercury Blackmax 150 no spark

orvman12 has pretty much spelled it out for you.

The Black/yellow wires from the switchbox are the 'Ground-to-kill', any short ini wiring to ground and you will cancel spark.

Disconnect both switchboxes from the motor harness right there by the switchboxes, the removes the whole wiring harness, ignition switch, lanyard switch, and the tilt switch from the circuit, leaving only the stator, triggers, and switcboxes.

If still no spark then clean the starter commutator and lightly lube the bushings so to be sure the starter is capable of cranking at or above the minimum of 300 RPM. You must have clean battery cable connections, BOTH ends and the starter cable.

If still no spark then you must test DVA output of the stator and triggers. Diagnosis is a process of elimination. If the stator and triggers all generate sufficient DVA then the only things left are switchboxes.

Since there is this NO RETURN on electrical parts, you want to test to be certain of what is at fault.

Do you have the CDI Ignition guide, FREE, at their site?

ISSUU - CDI Electronics Practical Outboard Ignition Troubleshooting by CDI Electronics

 

[Iceman66]

Re: 1989 Mercury Blackmax 150 no spark

My guess is that you have blown something, recomend like charlie and get your self a DVA-meter and Follow step by step here: ISSUU - CDI Electronics Practical Outboard Ignition Troubleshooting by CDI Electronics



(Page 81,82)

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

Follow-up: Ok so since the last time I posted I purchased a DVA meter and replaced all six ignition coils. The reason that I replaced the ignition coils was because I was getting good power out of the switchbox when I disconnected the leads from the coils but when I connected the bottom coil, all of the coils would lose power from the switchbox. I assumed that there was some kind of short in the ignition coil and wanted to replace them all to be safe. This morning I swapped all six and I still have my same symptoms. Has anyone removed a lead from a coil and see the proper voltage on the wire but lost it when it was reconnected? This is similar to putting a meter on a car battery and reading 12v but then doing a load test and having the battery test faulty. I tried swapping leads from the switchbox to different coils but no matter where the green lead with red would go, it would ground the outputs on the entire switchbox once connected. This occurs on the same leads on both sides and with them disconnected from the bottom coils I have spark on the remaining cylinders. Sorry if this seems confusing but I am losing my mind over this and running out of troubleshooting options. According to the troubleshooting procedures, if the switchbox has a good output it is good but I disagree. Any suggestions?

 

[Dukedog]

Re: 1989 Mercury Blackmax 150 no spark

when I connected the bottom coil, all of the coils would lose power from the switchbox.

What happens to tha other five if you only disconnect tha so called problem coil?

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

If the two bad leads are disconnected, the other four have spark.

 

[Dukedog]

Re: 1989 Mercury Blackmax 150 no spark

Are tha two "bad" ones on opposite banks?

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

Yes, cylinders 5 and 6 which is the green/red lead from each switchbox. When i hook up the lead from cylinder 3 to cylinder 5 it works but hooking up cylinder 5 to any other cylinder causes no spark on any cylinder. Same on the other side between cylinder 4 and 6. This leads me to believe that one lead is faulty on each switchbox. With everything connected, no spark but with the leads for cylinders 5 and 6 disconnected (green/red leads) I have spark on the other 4.

 

[CharlieB]

Re: 1989 Mercury Blackmax 150 no spark

Most likely the third trigger is defective. You may be able to prove this by switching the second and third triggers on a switchbox, then do the same on the other switchbox.

If the triggeris the problem then the 'no spark' will switch cyl's.

Always remember the NO RETURN on electrical parts. So try this to prove the trigger defect before you make the mistake of assuming the switchoxes are bad.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

If you read the earlier posts, I already replaced the trigger.

 

[Dukedog]

Re: 1989 Mercury Blackmax 150 no spark

When I asked what "bank ? I'm referring to tha different "sides" of tha motor. Tha "starboard" bank are 1, 3, 5, top ta bottom (one switch box) "port" 2, 4, 6, top ta bottom (other switch box). This makes 5 and 6 on opposite "banks".......and would indicate both switch boxes......

 

[sam am I]

Re: 1989 Mercury Blackmax 150 no spark

Tron,

I suspect the SCR and/or the high voltage charge cap(output circuitry , #5 or #6 cylinder, one or the other) inside of that switch box on that post that takes down your system/spark has bought the farm.

There is most likely shared circuitry internal to each switch box/es that is of course common to each three outputs and this common circuity is being loaded down and shutting off by connecting a coil on the bad post/output(hindsight is always 20/20 eh?).

i.e., when the good coil is hooked up, a shorted charge cap in the box for example could reflect the primary side of the coil's very low DC resistance back into the switch boxes' shared circuitry shutting the entire box off and perhaps reflecting issues as far back as the trigger/charging coils thus loading the entire system down and shutting it all off.

Shut all power off, dis-connect the offending grn/red wire from the switch box post and measure that post (NOT the wire to the coil) to ground, it should be about 350KΩ, any polarity.(assuming mine is close to yours, ya might just compare your own "known good" output/s against the suspect bad output as a sanity check)

Also, during same measurement, you should see a silicon diode junction........With black lead on switch box post and red lead to ground, use "diode check" function of meter, you should measure about 0.5 to 0.6 volts and an "open" when both leads are reversed.

If you don't have appropriate meter(not sure about your DVA/meter's functionality's) etc, switch the switch boxes, the problem should follow the switch box, i.e, the other grn/red wire now to the other other(#5 or #6, which ever it wasn't previous) cylinder should now shut down the ig's spark by hooking it up.

I assume by your question of "what's the voltage on the wire when dis-connected from the coil?" you're going down this path? I don't have, nor can I find that merc ever says "un-loaded/floating" voltages from the boxes but a static resistance test and/or swapping boxes might be enough to tell.

Those era/design CD Ig's typically just charge a cap up hundreds of volts from the stator's low/high "capacitor charging coils" and dump it on the primary of the coil(transformer actually) w a SCR(electronic switch that rectifies) when the trigger tells it too.

I suspect measuring the open circuit(no coils primary attached) post voltage while cranking you should see the cap charging up to some high'ish voltage, 200/300 or something'ish volts I'd guess, I'm not too sure, might be lower or higher.........but, not having a schematic of the box to know if they have arc protecting/limiting(typically a neon bulb), I'd try to stick w the above test/s first.

 

[CharlieB]

Re: 1989 Mercury Blackmax 150 no spark

Leave all the triggers connected correctly, disconnect only the White Bias wire that links the two boxes together. If there is a problem with the bias of one box it can block the other box from firing.

If you gained spark on onside then the nonsparking box is damaged. Change both boxes.