Spark has failed again-- why???

[wookiemail]

Still working on a 94 XP Seadoo. Nice condition, no rust or corrosion.
(There's barely any water in Colorado!)

There was no spark. I tracked it to
the CD module; bought one, replaced it and there was spark. I managed
to make it run--there was oil in the exhaust--I tracked that to too much
cranking without firing.

Now there's no spark again. I don't get it.

I don't believe it's the magneto generator. It has the right resistances.
It charged OK and both windings of the magneto section put out voltage
before and after.

The ignition coil has the right resistance. It worked for at least a little
while. It still has the same resistance. I have not let the ignition wires
run without a sparkplug or shorting the lines to ground.

If I had to guess, I'd guess the CD module is zapped again. What could
be taking it out I wonder?

I'm in some sort of ignition hell... I understand how these things work
but I do not have the lore to know what strange failures happen.

Any suggestions? Thanks, Bill Hale

 

[wookiemail]

I disconnected the white wire from the CDI module to the
RPM Limiter/Control box.

It now sparks just fine.

Something in that control module is commanding it
not to spark.

BH

 

[seadoosnipe]

Smart!

You sound like you really know your electronics. I'd have never thought of that. With the age of the Doo, the rev limiter switch/module must be bad. If all your other systems are working right. Don, who owns a PWC/ATV repair shop may read your post. He comes in from time to time and he may think your case really interesting and offer you some input.

 

[Wheels & Waves]

I disconnected the white wire from the CDI module to the
RPM Limiter/Control box.

It now sparks just fine.

Something in that control module is commanding it
not to spark.

BH

Bill, first I need to know if the ski has an aftermarket exhaust system with aftermarket electronics. It's been a while since I've been inside that model's box, but I don't believe that there is a separate rev limiter. The limiter is usually built into the MPEM. There should be 2 large modules (the MPEM and the VTS module), the voltage regulator, the coil, the starter solenoid and what SeaDoo calls an amplifier. The amplifier connects to the coil and acts like a stepper coil. If this is what you are talking about, it can be your problem. That ski has a separate start and stop switch. I would check to make sure your stop button circuit or kill switch (lanyard connector) are OK. If either of these switches are bad, you ignition circuit will shut off. Check there first.

 

[wookiemail]

Switches are OK.

Looking for a new MPEM for it 278 000 071

bh

 

[wookiemail]

mpem replaced

Thanks, Don.

I replaced the MPEM and sure enough that fixed it.

Now there is a new problem... after a while, the kill switches stopped
working.

Yet it will crank and start. So I'm convinced that the two switches
themselves are OK. If either is in the off position, the starter won't
run.

Sounds like another failure in the MPEM.

Bill Hale