1989 Mercury Blackmax 150 no spark

[88Glastron]

Last summer I bought a 1989 Mercury Blackmax to replace an early 80s Johnson. The Johnson overheated and I got a sweeper deal on the Blackmax which was incredibly clean and had great compression. I brought it home and ran it on a stand. The motor needed some maintenance done such as plugs, waterpump, carbs were rebuilt, so on. We did nothing to the ignition system. We transferred the harness and controls over to the boat and when we swapped the motor in we werent getting spark on any cylinder. The first thing we noticed was that there was a crack in one of the flywheel magnets so we replaced the flywheel. Still no spark. We followed the CDI troubleshooting chart and did the resistance checks on the components and everything tested sat as well as jumpering the safety lanyard. We tried disconnecting the harness and jumping the starter solenoid with still no spark. Next item replaced was the stator with no change.

At this point I would only be easter egging so I bring it in to a local shop and am told that they think either weak flywheel magnets or trigger assembly. I tell them that the flywheel was new and so they say trigger. I bought the trigger and installed it this afternoon with still no spark. I am at a loss now thinking the only other thing would be for both switch boxes to have gone out at the same time. I am looking for any input seeing as though the motor went from running on a stand to no spark once it was on the boat. Thanks in advance!

 

[Barnacle_Bill]

Re: 1989 Mercury Blackmax 150 no spark

Have you tried disconnecting the black/yellow wire on both switch boxes?

 

[Dukedog]

Re: 1989 Mercury Blackmax 150 no spark

Have you tried disconnecting the black/yellow wire on both switch boxes?

This plus kill switch at controls and in-line fuse above tha switch boxes...........

 

[Chris1956]

Re: 1989 Mercury Blackmax 150 no spark

Did you use the Merc wiring harness or the old Johnny's wiring harness? The Johnny control cables will not work. The wiring harness might work, depending on the year of the Johnny.

 

[racerone]

Re: 1989 Mercury Blackmax 150 no spark

Maybe the cranking speed / RPM is borderline.-------Check battery / battery cables / starter motor .

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

Did you use the Merc wiring harness or the old Johnny's wiring harness? The Johnny control cables will not work. The wiring harness might work, depending on the year of the Johnny.

I swapped over controls and wiring harness from the Merc.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

Maybe the cranking speed / RPM is borderline.-------Check battery / battery cables / starter motor .

Both myself and the outboard shop used two sets of fresh batteries to ensure that the cranking speed was up to par.

 

[Chris1956]

Re: 1989 Mercury Blackmax 150 no spark

OK, then disconnect the black/yellow wires at the switchboxes and see if spark returns. If so, the killer wire is shorted to ground somewhere.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

We checked the yellow/black and there is no short to ground. Can anybody confirm what I should see on a volt meter as an output of the switchboxes/input to the coils? The resistance checks are telling me that everything is sat but we still have no spark.

 

[Barnacle_Bill]

Re: 1989 Mercury Blackmax 150 no spark

Black with yellow stripe not the yellow/black. With the key off you should see a ground but not with the key on.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

Wouldnt we totally eliminate the kill switch by disconnecting the harness to the controls and attempting to start the motor by jumping the starter solenoid?

 

[Chris1956]

Re: 1989 Mercury Blackmax 150 no spark

yes, That would work. It may blow your rectifier though. Best to disconnect the yellow wires to it as well. Operate the choke (actually enrichener) manually.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

yes, That would work. It may blow your rectifier though. Best to disconnect the yellow wires to it as well. Operate the choke (actually enrichener) manually.

I haven't even begun to think about the enrichener yet because we haven't gotten past no spark. Why would jumping the starter solenoid hurt the rectifier?

 

[BatDaddy1887]

Re: 1989 Mercury Blackmax 150 no spark

You may need to replace the two power-packs (aka Switchboxes). They should only be replaced in pairs. When I bought my pair, I used Tungsten Marine parts, LLC....great deal on both.

 

[88Glastron]

Re: 1989 Mercury Blackmax 150 no spark

I have no issues buying a pair of switchboxes but I would really like some form of assurance that they are both bad. I replaced a flywheel because of cracked magnets but then replaced the stator with no change and trigger with no change and this is getting expensive. I am really looking for some form of proof that the switchboxes are both faulty. That is why I would like to know how to test the output of the switchboxes to the coils.

 

[sam am I]

Re: 1989 Mercury Blackmax 150 no spark

Yeah, think I'd be unplugging that cable, getting back to square-one.

With the cable COMPLETELY unplugged(kill circuit defaults open), my max(all factory wired max's) will fire up just by jumping the the starter at the solenoid. Don't even need a batt. to run after it starts in fact (not advised to do this, just saying) or even 12 V in the purple ig. circuit(12 V here just turns on the warning module, not needed just to test).

It should fire up and BUT, you'll need to Kill it by taking the BLACK/YELLOW circuit to ground with a jumper wire.

If no spark/fire up, check the BLACK/YELLOW circuit's resistance to ground, It should have high resistance........if it's not, nothing holds it to ground but, the ignition switch AND the mercury tilt switch.

 

[Chris1956]

Re: 1989 Mercury Blackmax 150 no spark

Operating the starter will cause the stator to power the switchboxes and generate spark. The stator will also power the rectifier, and with the rectifier disconnected from the battery (you wanted to disconnect the wiring harness, right?) it will likely blow a diode or two. Hence my recommendation to disconnect the stator from the rectifier.

 

[orvman12]

Re: 1989 Mercury Blackmax 150 no spark

yes, That would work. It may blow your rectifier though. Best to disconnect the yellow wires to it as well. Operate the choke (actually enrichener) manually.

OK, disconnecting harness will not blow your rectifier. You still have a path to charge battery from battery cable to the battery. As far as not having any spark, a v-6 stator for an ADI system has 2 charge coils and it is very unlikely that both are bad. You usuallly will only lose spark on one bank of cylinders if the stator is the problem. First thing you need to do is disconnect the black/yellow wire from both switch boxes. If you get spark you need to hook them back up and check and see if there is a black cylindrical switch located above the switch boxes. It should have a black/yellow wire running into it. It is a mercury switch that will kill the ignition if engine is trimmed to much. Unhook black/yellow wire from it and check spark. If spark does not come back unhook at kill switch at control box and finally at the ignition switch. If this doesnt cure your issue you will have to get a dva adaptor for volt meter. A regular voltmeter will not read the voltage coming out of your stator. Remove the blue wires from switchboxes and check voltage on both at cranking. You should have 100 plus volts on blue wires. If you do than your switchboxes are the issue but there again, highly unlikely that both are bad but i have seen stranger things.

 

[sam am I]

Re: 1989 Mercury Blackmax 150 no spark

Operating the starter will cause the stator to power the switchboxes and generate spark. The stator will also power the rectifier, and with the rectifier disconnected from the battery (you wanted to disconnect the wiring harness, right?) it will likely blow a diode or two. Hence my recommendation to disconnect the stator from the rectifier.

The batt is hardwired with lugs (not harness) and remains connected to the starter solenoid, else the motor wouldn't even turn over. We're talking about the circular 8 pin plug(I hope) It won't blow anything up to open that connector up and test fire the engine up. Been there, done that too many times.

But yes, running without a batt. and not loading the reg's down, which inturn loads the stators, allows voltages to float too high, making the reg's scream to try to hold outputs to 14 volts'ish, this tends to smoke things as things heat up. OP will not be doing this though by ONLY dis-connecting the 8 pin.

 

[BatDaddy1887]

Re: 1989 Mercury Blackmax 150 no spark

Testing procedures:


Page 1A - Testing outboard boat motor ignition parts