Announcement

**95 xp** · 01-20-2003, 01:04 AM

I don't know if this would cause it to fry but you should disconnect the bat. before charging. In any case something caused it to fry, is it possible any water got in the box, shorted wires etc. is the bat. the right 1 for the ski

**Bill O'Neal** · 01-20-2003, 11:59 AM

My guess would be that something inside the front magneto cover has dislodged (like a screw or tooth from the starter gear on the flywheel) and is shorting out the magneto.

I guess it's possible for an MPEM or rectifier to short out inside itself, but it seems odd that it happened right after an engine swap.
I would inspect all grounding cables and plug connections that go to the motor too. I would assume the rectifier will be shot too, as the current passes through it to the battery when the ski is running.
I am wondering why the 15 amp fuse didn't blow and save the mpem ?

If the VTS fuse is blown, it cannot allow electricty to pass through it.

I charge my battery without disconnecting anything. Never had a problem in 15 years.
I do not ever jump a jetski battery from a running car or truck though, too much amperage. Jumping from a 12V battery is ok.

Some aftermarket batteries have the posts reversed from the oem type batteries, so it is easy to install the negative cable to the positive post and vise-versa. Make sure that didn't happen.

Did into it and let us know what you find.

**Iron Flight** · 01-20-2003, 01:07 PM

Thanks for all the comments Bill!

I was thinking about the same thing in regards to something shorting out the mag under the front cover. When I tore the old engine down, my starter ring gear was really torn up, and there were a large numer of gear tooth shavings stuck to the magnet and throughout the housing. I did a "clean-room" job of cleaning them all up before re-assembly, but it's possible somthing hid and just came loose. The question I have on this though is why it didn't appear until after shutdown - wouldn't the mag shorting out while the ski was running cause it to quit running? Without a circuit diagram, it's hard to know....

I have double-checked all the wires disturbed during the engine swap - nothing appears out of order - positives to starter, ground wire to case...all look good.

Double and triple checked the battery posts on the new battery - they are correct (I doubt the ski would have started, much less run for three hours if it was wrong!)

And thanks for the vote of confidence for charging in the ski - been doing that for years, and couldn't figure it to be a problem. And when I jump from a truck battery, it is always with the truck not running...

I'll keep this post updated with what I find - still looking for an MPEM - Bill, you don't have a used one sitting around to sell, do you? 97 SPX, part Number 278 000 981....

Paul

**Iron Flight** · 01-20-2003, 02:22 PM

Fair questions....no water was found in the box - it was dry (except for melted potting), as was the bilge. And while the battery is not the stock one for the boat, it is a 12 volt, 18 amp/hr, just as the original - electrically identical, as far as we can tell.

I concur on a short! SOMETHING caused a lot of energy to flow through the MPEM!

What has me puzzled is that the boat has run perfectly, and was running perfectly right up to when I parked it . Whatever the problem was, it happened AFTER shutdown - I just can't beleive somehting this bad was happeneing while it was running, and the ski didn't miss a beat. My timing just isn't that good!

Speaking of timing, another quesiton for the experts. If I buy a used MPEM, what effect does this have on timing? I have been researching this in the manuals (very confusing!), and on the web forums for an hour, and am still not clear. If the MPEM has to be programmed for timing per a mark on the engine, how come we can drop in a "random" SBT engine and have no timing problems? And if that is true, then a "random" MPEM dropped in should be OK to...No?

Paul

"An Engineer with a wrench...a dangerous combination...."

**dank** · 01-20-2003, 06:32 PM

i have a good MPEM for 97 GTX if it is the same? I replaced it tring to fins a no-spark problem. Ended up being the stator.

**Bill O'Neal** · 01-20-2003, 11:13 PM

Commonly overlooked when cleaning broken teeth from a mag housing is the pieces that get into the starter area...... and come back to haunt you later. There are other places they hide too, in the stator and the trigger.

**Bill O'Neal** · 01-22-2003, 12:52 PM

Paul,
Pull the pipe, then remove the front motor mount bolts, all of them including the two that hold the mount into the hull, put a block under the front of the motor. Remove the mag cover.

The rectifier switches the AC voltage to DC voltage, then sends it to the battery, not the MPEM, so you shouldn't fry the MPEM because of a faulty rectifier. BUT, I'd buy a new rectifier anyway, as they do fail often, and they do not cost all that much to replace. I'll bet that you'll be buying a stator anyway, or at least a pickup.

**Iron Flight** · 01-22-2003, 02:29 PM

Thanks for the offer Dank - I think I've located an MPEM that won't make me take out a second mortgage.

Bill - good advice to check the well down by the starter - I am going to pull the front cover off and double check that nothing is in there before I install the new MPEM. I have also studied the manual, and can do the resistance checks on the stator assembly - but what do you think about replacing the rectifier as a pre-emptive measure? According to the manual, there is no way to test it without running it, and the way I see it, if it's putting out high voltage, then the new MPEM will be toast before I can test the VR (kind of a chicken and egg thing...) It seems to me if the stator checks out perfect, I should bite the bullet and replace the recitifier/VR assembly...

Oh - those that have been there, can I pull the front cover without removing the head pipe, or will I spend an hour trying to save thirty minutes by trying to work around it?

Paul

**Iron Flight** · 01-22-2003, 09:48 PM

I promised to keep you up to date, so here is this evening's status...I pulled the front cover, fully expecting to find some debris in the case, but instead, it was clean as a whistle. I found a total of one(1) little sliver of metal, that looked like what I had cleaned out before re-assembling the engine - it was stuck to the mounting point of the trigger coil. I checked the stator with a DVM, and it is exactly per the book - no short to ground from the yellows, and minimal resistance between yellows. I really checked the interior of the mag housing with a bright light, mirror, and magnifier, and am convinced it's clean. So I re-assembled the front end, and am satsified with that.

I got my new MPEM, but since it is going to be cold and miserable for a couple days, I think I'll take Bill's advice and get a new rectifier assembly - I am down to the fact that either there is a sleeper failure there, or the old MPEM just commited suicide. This boat always has had strange eletcrical flukes - just shut off every once in awhile - so that might be it. But why risk it?

I'll let the forum know when it's back up and running.

Thanks again for all the input!

Paul

**Bill O'Neal** · 01-22-2003, 10:27 PM

Paul,
It sounds like you are going about this the correct way and not taking anything for granted. I'm sure your boat will appreciate you for the care it gets. Good luck to you.

**Iron Flight** · 01-24-2003, 12:38 AM

Well Bill, thanks for the compliment, but this is getting really sad.....

I guess we took took one thing for granted - that was the VTS box. Yes, the 7.5 amp fuse was blown, so I figured it was out of play, but when I installed the new MPEM, and the new Rectifier, and hooked things up, the first thing that happened was that the 5 amp fuse blew (on the MPEM).

I checked all the connections again, unhooked the red lead from the Rectifier, just to make sure it was out of play (paranoid, I guess), replaced the five amp fuse, and when I put the key on this time, got two beeps - but after a few seconds, my helper said "I smell it again!" Yanked the key off, and checked everything again. Pushed the start button with the key off, and the fuel gauge came alive - then we smelled that hot smell, looked aft, and there was a little jet of flame coming from the VTS box. Looked frantically back at the MPEM, and there was a bubble in the potting over the same spot that the old MPEM melted (I think it is a power transistor). I quickly disconnected the battery, but I think it was too late.

Looking at the wiring diagram, I can convince myself that if the 7.5 amp fuse is blown, the VTS MIGHT pull power backwards through the MPEM - it's the only explanation I have. I read a tech article on the VTS on that other forum last year that said that a bad VTS could take out the MPEM, but didn't think about that till now.

Live and learn....just wish it wasn't so expensive! (at least I'm not paying labor - my local shops would probably have made the same mistakes, charged me for all the parts they burned up, and the labor as well....)

Got to go on a trip for a few days - I'll let the ski sit as it is until I get back, and stop being mad at it!

Paul

**Bill O'Neal** · 01-24-2003, 11:13 AM

Don't you just love electrical glitches? One would assume the 7.5 amp fuse would have blown before it melted the MPEM......

Must be your lucky week. Don't bet on the Superbowl.

**Michael73** · 01-24-2003, 02:15 PM

Ohh, I feel for you and this horrible mpem story.

There is a shop in Geelong, Victoria, Australia, called small coil rewinds, they rewind coils in motor bikes, jetskis etc etc,and they fix the local seadoo dealer mpems for them, not sure what they charge but it must be worth while, they told me they unpick all the potting compound and replace what ever is burnt out.

Hearing this is what gave me the confidence to unpot my vts module and succesfully replace all the components (except relays) and its been working fine for about 2 months.

I just used a hot air gun and a few flat head screwdriver, once the potting compound gets real hot it becomes fragile. And much easier to remove.

So maybe you could find someone over there that specialises in this field (ie winding coils and repairing cdi's etc etc)

Good luck.

**Iron Flight** · 01-28-2003, 01:01 AM

While I haven't collected my replacement parts to put the ski back in running order yet, I did get a chance to do some serious looking at the available wiring and circuit drawings (such as they are) while I was travelling this weekend. It is my strong recomendation for anyone with a VTS that has blown it's 7.5 amp fuse is to disconnect the purple wire going between the VTS and the MPEM!!

I don't have an internal circuit drawing of the MPEM, but from a drawing of the VTS, it is clear that the VTS does draw logic power from the MPEM, and if you have a bad enough short in the VTS, it can (did, in my case) draw too much power through the MPEM, and cause a power transistor to burn up. Bill asks a great question "why doesn't the 5 amp fuse blow to protect the MPEM?", but the truth about fuses is that philosophically, they really don't protect the "device", they protect the wiring upstream of the device (when the device shorts).

I was under the impression that if the VTS was blowing fuses, you could just leave it blown, and that was that - but this does not seem to be true! So my advice is to disconnect that single purple wire, and save yourself the potential of my headache - it won't hurt, and can save you big bucks...

Hopefully, my ski'll be back together for this weekend, and I can stop riding the wife's ski - and hopefully, it will warm up before then too!! (40 degree air temp last friday afternoon, and I was out tooling around the lagoon....)

Paul

Announcement

MPEM MELTED!!!

MPEM MELTED!!!

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment