1996 SeaDoo Challenger charging coil shorting

[Fordolet46]

I have a 1996 Sea-Doo Challenger with a 787 engine. I have had three charging coils short out and I can not figure out why. The symptom I keep getting is a blown 15 amp fuse in the electrical box in the engine compartment. I’m beginning to think there might be a problem with the magneto. All of the grounds look very good.

 

[funsummerahead]

What do you mean when you say "I have had three charging coils short out" exactly? Do you mean the rectifier? aka Rectifier - Regulator. WHATEVER you do please don't try a higher amp fuse...

 

[Fordolet46]

So the Symptom is that the 15 amp fuse blows. If I disconnect the electrical connector at the charging coil on the front of the engine the fuse will not blow until I plug the charging coil harness back in. I then test the yellow to black wires with an ohmmeter and they are shorted to ground.

 

[Fordolet46]

The original one let go on me then I replaced it with the one that I bought off Amazon and then I replaced that one with one that I bought used (oem) from a local mechanic. At first I thought there was an electrical issue causing this to happen however I’m beginning to think that the only thing that could be causing this is something mechanical like the magneto cover rubbing on the charging coil causing The windings to short to ground.

 

[funsummerahead]

I would agree with that. More than likely it has metal shavings from the starter / flywheel and they're on the magnets on the flywheel shorting it out. That is quite common on the 787's. Good chance you can take it apart and clean it and all will be good.

 

[Fordolet46]

Ok so I took one of the old ones and cleaned it up but the stator wires still short to ground while bench testing. So the charging coil is bad. There is a flywheel, charging coil and magneto on eBay used for $100. Do you think the starter needs replacement too? If I do it again I want to replace everything and be done with it.

 

[funsummerahead]

If it's not the metal shavings then yes the stator is bad. If your starter is working like it should then keep it, especially if it's original. After a few years there's some small metal shavings from the starter engaging with the flywheel which is normal that will accumulate on the magnets. This will cause a short. 1996 787's are also notorious for the pick up bracket breaking in there too, so take a good look at that. That generally causes a no spark issue and I don't think it's your problem but definitely look at it when you have that apart. Take that apart and check it, clean it and then check the stator in your engine. It may be good. After that THEN you can start throwing money at it.

 

[mikidymac]

It sure sounds like you have a shorted stator. The aftermarket ones on Amazon and ebay are junk so stay away from them.
For used parts I recommend Westside Powersports Sea Doo and he only sells tested used parts and actually guarantees everything he sells. He typically lets you send him your old parts and will test them too.

 

[Fordolet46]

I’m pretty confident of a shorter stator. The question is why? I think I’m going to yank the motor right out and repair on the bench. How do I disconnect the prop shaft? I don’t want to pull the jet drive out. I can’t imagine you would have to...

 

[Sportster-2001-951C-Stock]

If you remove the engine from the motor mounts, you need the alignment fixtures to realign the crankshaft with the driveshaft and jet pump.

 

[Fordolet46]

Is there a way to do it with out the tool? I have a dial indicator. Can I do it like a normal inboard motor with a feeler gauge?

 

[funsummerahead]

I would just remove the jet pump. It's a tight fit to the pull the engine and get it back in on the driveshaft and there's a little play just bolting the engine to the mounts too. Might as well pull the pump and check out the impeller and wear ring.

 

[mikidymac]

Is there a way to do it with out the tool? I have a dial indicator. Can I do it like a normal inboard motor with a feeler gauge?

No, there is enough play in the engine mounts that it is easy to get it back in and out of alignment.

You need the special tool because the engine is aligned to the back of the transom then the pump bolts to that. So either way you have to remove the pump to align the engine.

 

[Sportster-2001-951C-Stock]

The ID of the coupler is internally splined for the drive shaft, it's not a flange affixed to the drive shaft as an inboard has. The crankshaft end is threaded and the coupler is threaded onto the crankshaft, the drive shaft slides into the coupler.

So any misalignment of the drive shaft to the crankshaft will accelerate wear of the splines, perhaps dramatically, depending on how far out. I think you'll see more once you remove the jet pump.

Regardless, if you move the engine you'll need the alignment fixture,, which requires removing the jet pump, so it's best not to move the engine unless you have access to an alignment fixture (they can be rented, or perhaps borrowed).

On a ski of this age, considering things can move around over the years, it's not a bad idea to check the alignment anyway, with the pump removed.

 

[Fordolet46]

Ok motor is out. Just cracked it open. There is a lot of debris in the cover. Pics are attached. Flywheel looks good.

It looks like the magnito is rubbing on the stator. I welcome anyone’s input!!!

ScottyC

 

[mikidymac]

You are going to have to clean all of that really good. Also grab the flywheel and see if you feel any play at all in the front crank bearing.

Starter looks like it is at a really funny angle and not OEM from the picture?

Also from your dark oil lines, what oil are you using?

 

[funsummerahead]

You probably know this but don't lose or forget the white plastic piece for the oil pump to crank.
That runs the oil pump so make sure it's in when you put it all back together or you'll have no oil..

If the stator is nice and tight and the crank is not out of round that's most likely from some metal shavings coming off the starter and or flywheel from starting it. They get on the magnets and short it out.
This will happen over a long period of time and a lot sooner if the engine doesn't start right up. Dirty carbs or fuel system and people just keep cranking and cranking the engine till it starts.
I would get a can of electrical parts cleaner and hose off the stator and everything else.
Check the tightness of the pick up coil and check the wires too.
Ohm out the stator like you did before and see if it still has a short to ground. If it does the stator is bad. Away from the rotor / flywheel it could only be an internal short or bad wire.
If it reads good then the metal debris in there is the culprit.

 

[Fordolet46]

I’m being told it’s the mpem. Any idea how that could be?

 

[funsummerahead]

That is a possibility. It's expensive too, so that's why you want to check out everything else first as that is the "last resort." Read through all the posts here on your thread first. Looking at your pictures obviously something was rubbing from the flywheel to the stator. If it was only metal shavings on the flywheel contacting the stator then it would short out to ground. A new MPEM won't fix that. Clean everything real good and use a small cloth to clean up the flywheel and get all that crud out of there.

 

[Sportster-2001-951C-Stock]

Now, check continuity of stator coil to ground again. I believe you measured a short to ground before? That'll blow the charging fuse.

I dunno if I'd trust a coil that's been rubbing, maybe it's cracked or moving around? Sometimes the screws that fasten it in place fall out and attach to the flywheel magnets, then spin around and destroy the stator coil. Pieces of starter teeth will do that as well.

Lock-tight is important here as there's a lot of vibration, those screws must me tight enough not to come loose so they don't get caught between the coil and the spinning magnet.

So with that rubbing of the flywheel against the stator coil, it's possibly damaged (and shorted to ground) or was.

 

[Fordolet46]

Ok so here goes. So I put everything back together and it ran pretty good. I had some surging at high idle but overall it was good. I think it was just fuel related issues. I took it out today and ran it for about an hour, came home and pulled the air cleaner off and ran some sea foam through the carbs to clean em up from sitting all winter and ran it for a few minutes. It had good throttle response and I was going to go back out and try it again. Before I left I tried starting it once more and it wouldn’t start. After some troubleshooting I pulled the cover off the electrical box and checked the 15 amp fuse and it was blown again. I’m at a loss as far as what to do. I have no idea why it keeps blowing. Well it’s cause the charging coil is getting messed up. But why? I have no ideas left. Please someone help me. Any mechanics in the mass Rhode Island area?

ScottyC

 

[mikidymac]

Never, ever use seafoam or any "fix in a can", there is nothing on these uit will fix and it can actually hurt a 2-stroke engine since the solvents can remove the oil that a 2-stroke needs to live.

If you have a dirty fuel system do it correctly and take it apart and clean/replace the needed parts.