Sport Jet 90 no spark

[Daremo]

I am re-posting here because I got 9 views in the Mercury forum and I know there are other SJ posts in this forum.

I previously discovered I had a bad stator and since it was cheap enough to do, I have replaced the entire ignition system with the Crowley Marine discounted CDM system which updates this 1995 motor up to the 1996 ignition or the Sport Jet 95 ignition system as its called in the manual.

I still am not seeing any spark.

I have verified the following according to the service manaul.

Stator - 710 Ohms between Wht/Grn and Grn/Wht. (should be 500-600+/- 10% but 50 ohms isnt a big deal)

Trigger - Should be 1100-1400 between Wht/Blk and other 3 trigger wires. All 3 approx 1200 Ohms.

CDM module for Cyl one

Pin A to Pin C - Should be 1250 +/- 100 Ohms. 1280ish.
Pin D to Pin A - Diode test on fluke. Continuity indicated which is correct.
Pin D to Pin A - Diode test, reversing leads. No continuity which is correct.
Pin D to Pin B - Diode test. No continuity, which is correct.
Pin D to Pin B - Diode test, reversed leads. Continuity which is correct.
Pin A to Spark Plug Terminal - 1070 ohms (should be 1050 +/- 150 ohms, so its good also)

I just noticed that the manual does mention that you should check all 3 CDM's, so I will check them all for resistance and diode tests. I cant perform the voltage tests because I dont have the testing harness and I dont want to cut into the wiring.

I have isolated the Rev Limiter by completely disconnecting it, still no spark, and I had previously checked the safety lanyard switch, which I will check again.

I have replaced the ignition switch as I had never got the keys to this boat, so just bought a new one. I *THINK* its wired correctly, the engine IS turning over, but thats a possible area I have to double check as well.

So I'm running out of ideas as to why it wont spark. Any suggestions? The ONE other thought I had was the flywheel might be wrong, but CDI specs a replacement stator that fits both this ignition system and the previous one, so I am thinking they are one and the same.

Thanks!
Rob

 

[Jeff Walkowiak]

Re: Sport Jet 90 no spark

replace the rectifier, when it goes bad it destroys the power pack,, if you put on a new power pack and not the rectifier, the power pack will work the first time and as soon as you turn off the engine it will blow the new pack,, the charge windings are too close to the ignition windings,, a bad rectifier will allow ac current to create a spike or bastard field in the ignition circuit that instantly destroys the power pack.. I bet the plugs fired the very first time you tried your new stator and power pack but then it would not work from that time on

 

[Daremo]

Re: Sport Jet 90 no spark

Hmmm... I replaced that. I replaced EVERYTHING all at once.

This is what I bought.

http://www.crowleymarine.com/specials/Mercury_Ignition.cfm

The only component to the ignition thats original is the flywheel. Not sure how I can check the rectifier, but I can disconnect it and see if I get spark, which is something I was planning on doing tonight when I get home from work.

 

[Jeff Walkowiak]

Re: Sport Jet 90 no spark

does your flywheel have epoxied magnets if so they may have come loose and moved,,and the key on the flywheel needs to be good not deformed in any way, also try unplugging the kill wire as the ignition switch may be shorting to ground

 

[Daremo]

Re: Sport Jet 90 no spark

The magnets SEEMED like they were in the correct position, I can take a look again to be sure. There was a minor chip in one magnet on its bottom surface, it was about 3/8" long by about 1/16" deep, pretty minor.

The key on the flywheel was in good shape and I made sure I seated the flywheel with the key.

I had already disconnected the kill circuit, and I also discovered I need to replace the lanyard switch as its bad.

I am still thinking I need to check the triggers voltage outputs. Though I am going to disconnect the lines to the rectifier tonight to make sure its not taking the ignition side down also.

Any other thoughts?

 

[JUSTINTIME]

Re: Sport Jet 90 no spark

screw ohms
test in volts with a dva!

 

[Daremo]

Re: Sport Jet 90 no spark

working on it....

I dont own a DVA meter or a Peak Voltage Meter, but I do have an oscilloscope.

 

[Daremo]

Re: Sport Jet 90 no spark

Found a problem, magnets loose on flywheel. All of them to some degree.

Found this post here..

http://forums.iboats.com/showthread.php?t=123880&highlight=flywheel+sport+jet

And i have cleaned everything off, going to get some good epoxy and glue them back on. I also am trying to find a used flywheel rather than buy new, but I plan on replacing it eventually, just want to make sure this was my problem.

Any other BTDT on magnets and epoxy?

 

[Zamboni]

Re: Sport Jet 90 no spark

Those magnets must be correctly oriented-and if a mags cracked you now have 2 magnets so inspect them carefully.

The omc epoxy will do the trick, or an epoxy from industrial supply house.

 

[jpjones100]

Re: Sport Jet 90 no spark

My namne is John Jones in Michigan. I have a 95 sport jet 90 and have been told to replace the stator trigger assembly and rev limiter. I pulled the fly wheel and 3 of 6 magnets are off/loose. Epoxy for re-bonding the magnets was discussed, Industrial verses ???. Do you know what the specific epoxy is, supplier e.g. 3M and product code / version? Thanks

 

[webberz]

Re: Sport Jet 90 no spark

Does anyone have a manual they could supply? Thanks, Ryan
webberz@comcast.net