5 amp fuse in MPEM keeps blowing

[Aqua Chief]

So I made the mistake of using a jump box to start my Spi 570, the entire machine went dead so I opened up the MPEM box and found the 5 amp fuse was blown, I replaced the fuse and soon as I attached the positive battery cable it blew again, I put a 15 amp fuse in that slot and it blew that as well every time the positive battery cable is attached, any ideas where to start?

 

[mikidymac]

Get a new MPEM. The jump box fried it.

Never boost a seadoo from a running vehicle or boost box.

Don't waste your money on a cheap aftermarket MPEM either.

 

[Mickirig1]

Do the test procedure on Stator charging coil. Mine was fried and it did the same thing. A starter box should not send high voltage to the system. It is a 12.5 static voltage source. A running vehicle will be 13.5 to 14.5. Which will be too high of a voltage. What happened to cause this situation? Flooded hull? Unknown history? New Ski to you?

 

[mikidymac]

Voltage is not always the issue. It is the high amps from my understanding and jump boxes have been known to fry MPEM's.

 

[Mekanix]

Explanation:

There is a protection diode in the mpem. This thing is normally open circuit. When you jumped it, that diode was damaged and shorted out.
Its embedded into the potting of the mpem and what it does when it shorts is that it will connect the positive just after the fuse to ground. That means it will blow the fuse every time but the idea is that its supposed to protect the circuits after that. It normally acts as a voltage spike suppressor (it is a zener diode) and when it shorts it should release just as quick. But when damaged it just shorts out.

I have removed one and replaced it under the potting by digging it out and it does work but It was daam hard and not really worth it in the end. But hey "FOR SCIENCE !" lol

Your best bet is to replace the mpem. You can get a cheap one but it will likely fail on its own for no reason and at the worse time. Try a good used one or go new. Either way its what you have to do to get it running again.

 

[dieselndoo]

If the fuse spot called for a 15a fuse, it would've had one in there to begin with.

 

[etemplet]

is this the 5 amp fuse on top of the MPEM ? I want to look at mine but was afraid to put pressure on the cover to remove it. It looks like it is made into the MPEM. I chickened out. There are arrows on each side of the top. Does it slide ? I am working on a intermittent spark issue. Looks like I'll know this ski inside and out if I get this problem solved. LOL

 

[mikidymac]

Squeeze the two tabs and pull it straight off.

 

[etemplet]

I don't see any tabs and..... is the the 5 Amp fuse to which we are referring ?? Just making sure.

 

[mikidymac]

Sorry I was thinking the newer MPEMS.

 

[etemplet]

In the manual it shows this fuse removed from the MPEM I just don't want to break anything. This may not even be a a problem so I don't want to make it one. Ha ha.