No Spark 2003 Mercury Big Foot 60HP 2-Stroke

[klze]

Hello Everyone,
I'm having hard time getting my spark back after electrical fire
starter engages, engine turns over but no spark to all 3 CDM's!

Seems like I checked it all, everything is getting ground and 12v
Stator is within spec, Rev limiter is brand new.
Ignition switch continuity test is good.
disconnected Black/Yellow wires going into CDM harness and still no spark.

Replaced following parts already in hopes for spark:

Complete Harness with key (used)
Flywheel (used)
Stator (used)
Trigger (used)
All three CMD's (used)
Rev limiter box (new)
Voltage regulator (used)


Here is the story,
had this engine for 4 seasons now, all was working great.
when I got this motor, wires were somewhat cut half way on the harness so an universal harness was made back in the day, everything was traced wire by wire by the book.

recently had electrical fire, can't blame my harness here I would say, have found green corroded resedue on the wires inside burned Voltage Regulator, makes me lean towards known issues of this boxes going bad.

having said all that, I think it's something simple with switches?
the reason I say this is because right now I'm running a switch to Yellow/Red wire for Nuetal switch, otherwise engine doesnt even turn over.
But I still think something has to do with that Black/Yellow wire/switch,
because in my other harness I had a switch going from Black/Yellow to ground.


Everyone is welcome to chime in, I know you guys are out there,
thanks in advance for all the help, advice and tips!!

 

[pnwboat]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

Sounds like you've got more than one problem. The fact that you have to run a separate switch as your neutral safety switch tells me that either your wiring harness is bad or ignition switch is mis-wired or bad. Something is not quite right there with the harness and ignition switch. That should not be a show stopper though.

On to your main problem with no spark. These motors don't need a battery to run. The only reason for they have a battery is to turn the starter over and run your electrical accessories. You can disconnect the battery completely and rope start the motor and it'll run just fine. Most obvious thing to check is the ignition kill circuit. This is the black wire w/yellow stripe. You need an OHM meter to check resistance. Disconnect it from the harness and measure between the wire coming from the CDM's and ground. You should read "open" or no continuity. I suspect that maybe the insulation has melted and is shorting to ground?? Hook it back up and check between the wires and ground. The only time you should see continuity to ground is when the ignition key is in the "off" position. When you turn the key to "on", it should read "open" or no continuity.

 

[klze]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

I will give it a try, by disconnecting the large harness plug at the engine.
will need to jump the starter solenoid to crank the engine while checking for spark. Never thought of that before, sounds like a good way to eliminate the harness & switches.

I did OHM test for "open" or no continuity a few days ego.
I did it in two steps, I disconnected Black/Yellow wire going to CDM's so that I can test the harness wire seperate from CDM.

Put key in "ON" position and had no continuity at the harness Black/Yellow wire.

But when I did same test on the CDM side, I get 1,500 ohms with key in "ON"
position instead of "open" or no continuity, making me think that maybe CDM Black/Yellow wire is touching ground somewhere at all times?

Since I did this test prior to this post, I will run no continuity test one more time.

 

[Bob_VT]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

I am not familiar with that motor but.....

Green corrosion usually happens in NON-marine wiring. Once you pick up green corrosion it is like a cancer. You should also check all your other wires for it. When a wire corrodes the resistance goes WAY up.

There have been people who have seen their main power + & - actually glow from heat and the increased resistance will screw up an entire electrical system making it impossible for some parts to work right.

I just completely re-wired my boat and even installed real heavy duty battery leads. I was lucky and found that the local Interstate Battery store stocked the bulk wires at a great price.

I am going to pass the buck and hopefully achris will chime in. He has a good handle on the newer Merc's.

Just another point....... corrosion in wires will also screw up diodes inside of electrical boxes.

Sorry to hear about the fire..... want to explain?

 

[klze]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

My Voltage Regulator was so glowing that it got on fire!
Thanks for heads up, I alreday sent PM to achris to chime in...

I am not familiar with that motor but.....

Green corrosion usually happens in NON-marine wiring. Once you pick up green corrosion it is like a cancer. You should also check all your other wires for it. When a wire corrodes the resistance goes WAY up.

There have been people who have seen their main power + & - actually glow from heat and the increased resistance will screw up an entire electrical system making it impossible for some parts to work right.

I just completely re-wired my boat and even installed real heavy duty battery leads. I was lucky and found that the local Interstate Battery store stocked the bulk wires at a great price.

I am going to pass the buck and hopefully achris will chime in. He has a good handle on the newer Merc's.

 

[jtexas]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

You can run the motor without the battery, but not without sacrificing the rectifier/regulator. Corrosion/bad connections in the charging circuit will do the same thing.

don't forget, the motor has to spin at, what? 250 to 300 RPM (not sure for mercs), to generate spark. don't forget to recharge the battery if you're doing lots of cranking.

not sure what is meant by " running a switch to Yellow/Red wire for Nuetal switch" -- you mean you've wired across the neutral safety switch?

If I am interpreting this correctly -- "But when I did same test on the CDM side, I get 1,500 ohms with key in 'ON'" -- then I can't imagine a possible result other than what you suspect, that the kill circuit is accidentally grounded somewhere along in there, to include maybe inside the module itself. See if I read you right: you put one probe on the black/yellow wire at the point where you disconnected it, and the other on any good ground? Good idea, repeating the test just to make sure. I assume you know that if your fingers are touching both leads, you'll measure the resistance of your body? Should be neighborhood of 1.5 to 2 meg or so, but it's lower when you're lying (try it).

Just for future reference...as you are discovering, randomly throwing parts at a problem can get pretty expensive; most if not all of the components you mentioned in your original post can be tested. On the other hand, having a complete set of spares is not such a bad thing.

FWIW I can confirm from personal experience what VTBob says about automotive wiring turning green (and by "green", I don't mean "environmentally friendly").

 

[achris]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

The first question is do you have a factory manual that you are working from? If not, click HERE to download, password is <ribforum>.

I would tackle this by removing (disconnecting) anything that is not essential to creating sparks. That means unplugging the harness and using a remote starter switch (as you discovered a few posts back), and the rev limiter. I would even go as far as disconnecting the voltage regulator for the purpose of testing.

Now disconnect all the CDMs. Plug #1 in and check for spark. Unplug it and plug #2 in, check for spark. Unplug it, plug #3 in and check for spark.

If you still didn't get spark on any of them, you have a trigger or stator problem. Using an ohm meter and a DVA meter check the stator and trigger as per the book.

Chris.................

 

[klze]

Re: No Spark 2003 Mercury Big Foot 60HP 2-Stroke

Thanks for all your help guys!, wait until you hear this story.

To Crhis:
Yes I do have service manual but in book format, pdf is great to have as well, thanks!

Disconnected wiring harness along with stator without any results.

I did continuity test again on that black/yellow wire to find out that there is no ground going to CDM harness. Took all the lume apart to see if anything is wrong with the wiring, all looked good and intact. There is continuity from that black/yellow wire to all CDM plugs and all plugs have ground aswell, but no ground to kill wire (black/yellow) that made me think that it's time to ohm test all the coils since seems like nothing else is left.

CDM#1 is feeding #2 & #3 and vice versa, so I decided to start with the first one. Didn't even get to testing it took it off so i can access ABCD pins better and found my problem!
Pin A, the black ground wire was bent and coils didnt get ground to even have any chance of fireing!

Wow, It's just unbelievable that I went thru all tests and replacing parts, hours of thinking to just find one small bent pin
Ooh well it's always like that when you look for something big it's right under your nose....


not an everyday problem, but something definitely to consider!
I would have never found this if I didnt take that CDM off and looked at plug pins, not to mention that the third one is not even accessible unless you take it off.