Seadoo gsx 787 blowing 5A fuse and not doing a thing when hitting start/stop

[Zachlopez88]

Hey guys, I have a 97 seadoo gsx 787. got Home from a ride one day and parked it . i came back out a week later to start it and absolutely nothing happens when hitting start button. 5A fuse keeps blowing where the front storage compartment is. replaced starter solenoid and fuse. As soon as the new fuse hits the connectors, POP. Blows over and over again. I read a similar forum but turns out a rat chewed the guys wires and that’s not the case for me. Every wire is intact and every plug is dielectric greased. Has anyone else had this problem?what could this be? Thanks in advance

 

[POPPS]

Usually,,,it means your MPEM is done,,,

 

[mikidymac]

And the most expensive MPEM’s are the 97’ GSX if you can even find one.

 

[azsxr]

I’ve seen this happen with metal shavings getting on the pick up in the mag housing and shorting out.

 

[Zachlopez88]

Thanks for the reply’s. I went on to unplug each and every plug/harness possible in the ski and still blew each time.. chased each wire from the harness that it always blew on and found 0 issues with the wiring . Unfortunately I think the computer is fried.

 

[mikidymac]

That would be a bad MPEM.
You could try replacing the diode as @etemplet has done a few.

 

[etemplet]

Plug in the MPEM and check for power feeding back to the terminal where you plug in the 5 amp fuse. If you have power there naturally it will blow the fuse but it is a check you need to do. So if the power is feeding backwards you have a blown diode For my ski the culprit was a bad rectifier. Post a picture of your MPEM.

Are you checking the source of the power feedback? That must be located or you'll wreck the new MPEM. I think fixing your MPEM is a good way to identify that you've solved the problem. It was a pain in the azz but you get to control the time frame and the cost.

We sure could use a guru that knows how to do this kinda stuff. That potting goo is miserable to get through.

 

[Zachlopez88]

Plug in the MPEM and check for power feeding back to the terminal where you plug in the 5 amp fuse. If you have power there naturally it will blow the fuse but it is a check you need to do. So if the power is feeding backwards you have a blown diode For my ski the culprit was a bad rectifier. Post a picture of your MPEM.

Are you checking the source of the power feedback? That must be located or you'll wreck the new MPEM. I think fixing your MPEM is a good way to identify that you've solved the problem. It was a pain in the azz but you get to control the time frame and the cost.

We sure could use a guru that knows how to do this kinda stuff. That potting goo is miserable to get through.

So check to find where the mpem has power? Because it’s not supposed to have power coming back to it? Is that what you’re saying?
A while back I forgot the plugs and it flooded the hull so I just assumed it took on water somehow but didn’t understand because i was able to get the water out of the engine and it ran for about 3 months after that . Literally parked one after riding 1 day and the next day came out and it didn’t do a thing . Also, should there be a ground coming out of the black electrical box in the back and onto the battery. I saw another post on here of a 96’ gsx that had a ground right there but mine doesn’t have it and I don’t ever remember having it

 

[etemplet]

Download the manua herel Seadoo Manuals if you don't have one and go to the back and get the wiring diagram. You'll be able to answer the questions you are asking.

I'd start with checking the wires on that rectifier. Do some ohm checks. If there is continuity between any of those wires and black ground wire you'll have problems. In the manual it will give you ohm readings on the yellows. If I remember correctly around (.1 to .7 ohms) That's a start good luck.