Mercury Sport Jet 90 Engine Problem need advice

venxxxxx

Seaman
Joined
Apr 25, 2011
Messages
55
Re: Mercury Sport Jet 90 Engine Problem need advice

Nicely done. Atleast its now running and didnt cost half the amount the service folks predicted. I hate and never taking any of my toys to have it serviced because of too many bogus people who took a few classes and get certified to bull. The last time anyone "certified" to fix my toy cost me $500 for a simple front wheel alignment which he said 'would have to take it all apart then put back together' - NOT one screw scratched....so there goes his lies and my wallet had to cover his mouth for it.
Honest people on this planet are about 1% left and a diminishing minority.

Anywho,

You should get it perfected in time for the June fishing trip!

Waiting for you pics still ? :)
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

IMG_20120522_204217-1.jpgIMG_20120522_204240-1.jpg
 

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aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

The plot thickens Me and my daughther went down to the local boat launch to see if the boat will go,
on the way in to launch my trailer tire got slashed wide open in the water cause unknown.

Anyways I launched the boat I got in and tried to start it no go tried every combination no go so changed the tire and headed home.

I rechecked compression good 140psi across the 3 pistons got fuel, checked spark by grounding all 3 spark plugs and I only get spark once while cranking then nothing. If I tried again I get spark just once and then not again during cranking.

BTW the boat has the red stator conversion done Stator is good 650 ohms white green to green white

So I tested the trigger and this is what I got Brown to White/black 456 ohms, White to White/black 660 ohms, Violet to White/black 1.05K ohms

Looks like its time for a new trigger
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

Here is what the inside of a trigger assembly looks like without the potting compound this is for a SJ90 the 120 has an extra coil :eek:

IMG_20120523_224432-1.jpg
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

So today I finally got my trigger assembly after 2 weeks of shipping Wow lo and behold its the wrong part# they got me the cdm trigger assembly.

So much for my fishing trip this weekend guess i have to borrow beg or steal another boat.

This sucks ***
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

This freaki'n boat is a nightmare I wish I never bought it :-

So I got the right trigger installed it still no spark. Let me correct I get one lousy spark on one spark plug every few tries crancking the engine but nothing after that.

This was the same symptom I had before I replaced the trigger but the trigger resistance was out of whack the stator is good. Trigger is new disconnected kill wire coils are good had to replace one due to the ferrite core being broken the only thing left is the switchbox after that if it still don't work I'll just burn the piece of crap (SHhhh Don't tell My insurance Co)

Help me please where is a good place to buy a new cdi besides the stealership in Canada
 

Anders67

Petty Officer 2nd Class
Joined
May 23, 2012
Messages
117
Re: Mercury Sport Jet 90 Engine Problem need advice

You have the leater CDM modules, ore the earlier?.

The man who made this engine electrical i hope was put in tar and feathers, and hanged.


If you have a bad CDM it can give the rest ( stator, trigger, CDM ) all kind of readings. It can also kill the one that?s god, beside the one thats bad.

What do they cost over there?. Her in Sweden i payed like 100-110 USD.
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

I have the earlier CDI module aka Switchbox with the red Stator and Adapter. Initially it started after a 1 minute then it got harder to start, then finally after riding for about 50 minutes started to loose power at wot it would only run at 3/4 throttle.

Next time I took it out I could not get it started checked for spark had none, then while the spark plugs where out and grounded I cranked the engine and I got one just one spark on one of the spark plugs when I first turned the key to start then nothing during the cranking.

If I tried it again I would say out of 5 tries I would get the same result twice.

I started to diagnose the problem by checking the kill wire, rev limiter, key switch for continuity and to see if there was any voltage on it it all checked out, no voltage on kill wire at any position and continuity only in the off position.

Next I ohmed the stator green/white - white/green it was 675 ohms, then checked the trigger and got 1100, 657, 465 ohms clearly way out of whack so ordered new one they sent me the wrong part (CDM Trigger 828302A1) so I had to return it and get the right one (CDI 3cyl Trigger Assembly 817029A9)

I installed it, all the trigger wires read 1230 ohms so its good still no spark, then I checked the coils I do not have any voltage at the coil primaries, I measured all 3 coils and are whiten specs one had a broken ferrite core so I replaced it with a new one (Ignition Coil 7370A23).

Still no spark, the only thing left is the switchbox. Probably got killed by the bad trigger (burns SCR inside switchbox) so I ordered new switchbox and waiting for it to arrive before I can test it again.


I also disconnected the rectifier/regulator and made no difference charging coil is on spec.

The switchbox cost me $272 USD with shipping CDI Brand (CDI 114-4953).
 

Anders67

Petty Officer 2nd Class
Joined
May 23, 2012
Messages
117
Re: Mercury Sport Jet 90 Engine Problem need advice

Well sounds like you done your mathe.

Yes if all other things ok. sound like the guy between = Switchbox.

Not uncommin.

I have never in my life seen a engine electrical, that are more problematly than this. Made to be safe. But built so one part kill another. :eek:
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

I know what you mean its a freakin nightmare they should of left the chrysler prestolite ignition system instead of putting mercury hacked together ignition or merc should of spent a few more $ in protection components inside their switchboxes
 

Anders67

Petty Officer 2nd Class
Joined
May 23, 2012
Messages
117
Re: Mercury Sport Jet 90 Engine Problem need advice

2012-02-26 14.56.08.jpg


I?l tell you . i neraly went to the koko-nest over mine 120XR.

Changed stator, not better.

Changed trigger not better.

Changed Reticif. . Started to volt-load battery ok., but engine electric not ok.

Changed Spark plugs. Not ok.

Canged 2 CDM unit . Not ok.

Canged 4 CDM units. Ok. for a while but then , the SAME PROBLEM !!!!!!!.


Put two old CDM and two new on, and the dammed engine runs ok... Probaby some fault on the new CDM units. One was stone dead, one dead on low rpm. . . :eek:



On mine it was probabl. more then one problem.

Check. the grounding fom the differnt units too. On mine the grounding wiring from the CDM unit vas so-so. And with the low-voltage from the trigger it can make problems.

I?l think the manily problem on mine was, probably had the former owner , pulled the battery lines of with the engine running. Makeing electrical components to brake down. And then one part kills another.

Otherwise disconnect all yellow/black also and check. Thats the kill-line. Also the rev. limiter.



Regards from Sweden. :)
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

Nice boat SJ90 or SJ120
 

Anders67

Petty Officer 2nd Class
Joined
May 23, 2012
Messages
117
Re: Mercury Sport Jet 90 Engine Problem need advice

Hi . It?s a 1996 Sugar Sand Mirage.

Probably not run mutch, becaurse the stator that was put on (red) was mounted 1998. And it was mouted in wrong position on the engine ( you can bolt in on in different positions).

Milled the head of a bit, new head gasket and put Boysen reeds on. Now it runs okay/good.


Hope you got the engine togeather. Sounds like the switch box.


Regards Anders
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

I hope so too! I did get Chris Carson reeds installed and it does make it rev smoother that's when it actually runs.

I ordered the switchbox on Monday Morning and I paid for express shipping 3-5 day delivery hoping to get it by Friday, checked this morning and shipping is still pending. This sucks Incompetence everywhere no wonder the whole world is going to hell.

I guess no boat this weekend either Hopefully I get it running by December
 

Trailratethisfx4

Seaman Apprentice
Joined
Jun 7, 2012
Messages
46
Re: Mercury Sport Jet 90 Engine Problem need advice

I just orderd my switchbox same part number as you last night and it should be here on friday or saturday, hope friday cause if this part fixes my no spark problem then i want to spend the day off on the lake saturday. I just cant belive how much crap i have been through in the past few weeks trying to get this boat to run. Aksor i really hope the switch boxfixes your SJ as well as mine.
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

I hope we can both get it working and enjoy the rest of summer without any incidents

I know what u mean it was quite a trip but I now this boat inside out :)
 

Trailratethisfx4

Seaman Apprentice
Joined
Jun 7, 2012
Messages
46
Re: Mercury Sport Jet 90 Engine Problem need advice

if this doesnt work, im gona look for the cdm conversion kit. that way it will get rid of every what if problem. The block in my boat is new so im thinking who ever had this boat befor me bought a new block and just put a bunch of miss matching elc parts on it, and none of it worked so they sold it. when i bought it the guy said the stator was bad but it wasent, its something else.
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

A bit of an update today !

Don't ever buy anything from a Marine Supply Direct so far it looks like some clown running it out of his basement, my CDI ignition is still not here I ordered it on June 12,

I called him twice requesting tracking numbers got nothing even though he promised to email it to me. So I will be initiating a refund request trough paypal to recover my $270.

Monday I decided that I can't wait any longer so I decided to take apart my original CDI unit I spent 3 hours scraping potting compound to get to the board and get all the rubbery crap of the circuit board without damaging any of the components.

I then I ordered my parts from Digikey for a whopping $6 and received them today, replaced the 3 small SCR's that got fried when my trigger failed and my CDI is once again operational.

Whohooo! :D

I got spark on all 3 cyl now I got to put the board back into it's case so it's easily removable without scraping a ton if I ever have to fix it again.

Will post some pics of the guts of the original Mercury CDI. Part# 18495A26
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

Here is the guts of the Mercury CDI unit. Pretty boring 6 scr's 3 pulse transformers to isolate the trigger from the high voltage, 1.5uf 400v storage capacitor a bunch of diodes for rectification and spike protection and resistors.

View attachment 155121
 

aksor

Petty Officer 2nd Class
Joined
Apr 21, 2009
Messages
150
Re: Mercury Sport Jet 90 Engine Problem need advice

funny my posted picture disappeared from the previous post. So here it is again!

IMG_20120627_172434-1.jpg
 
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