98 Speedster- When one motor starts the other dies

[Sportster-2001-951C-Stock]

Okay, I see. If you can post the specific schematic, any of it, it might help. As far as I know though, there were no schematics published for the 2-stroke twin boats, even for my 2-stroke boat I use the 951-XP ski schematic and I'd guess you'd have to adapt as well.

Agreed, hard to imagine how a new starter by itself would cause this issue.

How about if you manually jump the S starter solenoid while P is running instead of attempting to start using the MPEM start button? I guess the result would be same since the P doesn't die until after S is running. Bizarre, there must be an explanation....

 

[Oljoe]

It’s as mysterious as the heads on Easter Island, but surely it will rear its ugly head sometime. Trial and error...

 

[Sportster-2001-951C-Stock]

Sure. If you don't mind though, post the solution once you've found it. This is really bugging me, lolz.

 

[Oljoe]

Will do, thx again for the help

 

[rgardner928]

Also, keep the OEM starter (assuming it's an OEM) b/c the quality of aftermarket starters is notoriously poor, it's better to rebuild the original starter using the rebuild kits.

You can rebuilt starters?? How..please explain!

 

[Sportster-2001-951C-Stock]

The OEM Denso starters are considered much better than most aftermarket starters, the armature shaft of aftermarket starters for one thing are too soft and flex too much. Some people have reported reasonable success but you may not reach the same conclusion. Always inspect your internal magnets for damage, if the internal magnets of permanent magnet starters are broken, the starter will not perform correctly.

There are Seadoo Denso starter rebuild kits available from numerous sources, you want a complete kit listed for your model, year and engine type which includes new sealing o-rings, brushes and bushings.

Pretty sure the kits include instructions, if not open a thread with specific questions and I'm confident a small army will join the discussion offering numerous tips and tricks.

The above parts tab at top of this page leads to the sponsor of this Seadoo forum with phone number and I'm sure they can provide a kit for you.

Enjoy, and never throw away your old Denso original starter!

 

[Oljoe]

Sure. If you don't mind though, post the solution once you've found it. This is really bugging me, lolz.

Ok, update: I guessing it had something to do with the Mpem. Got tired of fighting it and had a good Mpem out of a 96gtx. So I used the gtx mpem on the port side and everything else is still run off the original mpem. Now both motors fire and run at the same time. The only trick was I had to run a hot and ground wire to the original port side coil wires feeds and added a second dess post. I wired the tach so it’s operational, along with a second beeper.

 

[hotrodssnova]

Nicely done. Make sure you get the mpem in the ebox where it will be waterproof.

 

[Sportster-2001-951C-Stock]

Good thinking, nice to hear it's back working and thanks for the follow-up!

One more thought, and totally optional of course but it might be worth considering a single panic shutdown option where tugging on a single lanyard shuts both down. Other than maybe that, this is an elegant solution IMO.

 

[Oljoe]

I placed the dess post right next to each other and have one lanyard with the two keys. The keys are colored so I know which one goes to what post.

 

[Sportster-2001-951C-Stock]

Perfect!

 

[rgardner928]

So you basically did an MPEM conversion learning on your own. Congratulations!

 

[Oljoe]

So you basically did an MPEM conversion learning on your own. Congratulations!

A little overwhelming at first but not bad at all looking back on it.