1995 Seadoo HX turns over as soon as battery is connected

[seadoodle]

I recently bought a Seadoo HXand it has this strange phenomenon. As soon as you connect the battery, the starter turns over. So here's what I tested so far:
1) I unplugged the plug is connected to the starter solenoid in order to rule out a sticky solenoid. The engine did not turn over. So I think that rules it out
2) I tested the start/stop switch with an ohm meter. It read open and when depressed it was closed with 0 ohm (as specified in the manual) so the switch is ruled out. Just as a side note, how does the switch know to start the starter or stop the engine
I'm just curious
So is it the MPEM bad? The previous owner replaced the MPEM with an aftermarket. If i buy one, should I go with a used OEM or bite the bullet and get another aftermarket one because I know my XP as one and it works.

 

[esahlin]

I have a very similar problem with my 96 XP. I bought a new Arieltek MPEM for it and the ski starts and runs but when you attach the battery cable there is a spark at the cable attachment and you can hear the starter solenoid click. It doesn't try to turn over though. Ive only tested this on the trailer.

If you leave the battery connected the ski starts and runs fine on the trailer.

Ive unhooked the yellow/black wires from the starter solenoid and still get the click and spark when battery cables are attached.

Ive checked the start button and left it unhooked and same result with attaching the battery cable. Thought maybe the start button was stuck "on".

Ive checked the dess post and left it unhooked and same result with spark and starter solenoid click when attaching the battery.

Stator is brand new and engine just fully rebuilt. All battery cables, starter solenoid, ground cables, coil and much of the wiring is also new. After engine rebuild, and restoration of this ski it has never been on the water I'm trying to get it ready for its first engine break=in on the water.

Rectifier is original and old.

I'm wondering if the rectifier can short out and cause a continuous draw on the battery and still the engine will run fine on the trailer?

 

[mikidymac]

The aftermarket MPEM’s have been known to be crap out of the box.

 

[esahlin]

Ive heard that the aftermarket MPEMs were hit and miss. I thought that they have been out on the market so long now that I thought for sure they had their quality control in Brazil figured out. My Arieltek board said it was tested November 2017.

So, I replaced the rectifier with a new one (as in new meaning a new NON-oem one off of eBAY.... I had it laying around) and I received the same result of a small spark on pos batt cable attachment and a click of the starter solenoid.

I left the entire MPEM or the entire grey box unhooked (so no power to MPEM) and left the rear starter solenoid/ battery cable/coil box installed and attached the battery cable and no solenoid click or spark on pos battery cable attachment. Did this to see if there was something shorting with the rear E-box.

I hooked up the 4 wire connector from the rear electrical box (white wire/red wire/brown wire/yellow red stripe wire) to the MPEM/front grey box. My white spark/coil wire is brand new. My yellow/red stripe wire to the starter solenoid is brand new and the red and brown wires were checked for continuity and checked OK.

So with just the 4 wire connector connected to the grey box/MPEM I get the starter solenoid click and the small spark when attaching the pos battery cable.

No fuses in the MPEM or anywhere else were ever blown in this entire endeavor.

I guess something is shorted when power is attached to the MPEM board.

But if I leave the pos battery cable on the motor starts and runs, gauges work, buzzer beeps appropriately.

Mindboggling.