Michael1973

Hello PWCForum guys and gals, I sold my 97 XP a few years back but now have a 97 GSX at a good price (by Australian pricing). I Brought it not running.

The problem is it has no spark at the main plug leads. Previous owner told me this was the fault also.

What ive done so far:

The battery is fully charged and has been load tested. Its ok. The seadoo gives two beeps when the lanyard is connected and the dash gauges display normal info. Ive checked the 5 mpem fuses and 1 fuse in the rear box with multimeter after removing them, all ok. The vts functions normally also and IS connected.

Ive put a 12v test light and earthed it direct to earth lead from the battery on the engine and probed the white wire going to the coil in the rear black electrical box where the starter solenoid is. The test light DID NOT flash. I tested this with the spark plugs out while cranking over. I tested continuity from the same white wire up to the large plugs at the mpem. There IS continuity.

I removed the magneto cover (bigger job than I thought), I was hoping the trigger coil had broken its mount, it HAD NOT. The stator looks even in color visually, not burnt, no dark spots, minor metal particles (more like dust) which i will clean out before reassembly, the multimeter test on the trigger coil (yellow/white and yelllow/black) 0.242 ohms, NO continuity to the housing on either wire. The trigger coil measures the same resistance on the same wires at the large mpem plug also. The stator wires (yellow and yellow and yellow) all three have NO continuity to the housing or the black earth wire. The 3 yellow wires have 1.0 ohms between them all. The cup mounted on the flywheel appears good, with the 2 raised spots on the outside appearing normal. Still no spark or power to the white coil wire using test lamp.

The previous owner said the ski had been jump started which damaged the 5amp fuse diode in the mpem, the diode was replaced and the ski ran normally for a couple of weeks, he said the battery went flat a few weeks later, and now there is no spark. I removed the mpem, and noticed the potting/encasing compund is almost clear, you can still see small traces of the old black original compund, I also noticed that some of the clear compound is starting to lift off the circut board. I only looked at the back of the mpem. The regulator/rectifier was replaced when the mpem was repaired, it still looks new, NO corrosion around the sides.

Its seems the mpem is the last thing to check, other than the physical terminals from the large connectors into the mpem. Im handy electrically and dont mind replacing tiny electronic components, Im often replacing capacitors and voltage regulators in electronic gear.

Have I missed anything on my journey to the mpem being faulty?

Any advice on where to check on the mpem circut board and what to look at, diodes etc, hopefully something will be obviously burnt or broken. I will post pictures of the mpem if I open it up.

Apologies for the long post, but I wanted to provide as much info as I could.

I know its the cooler season in the USA, but its summer in Australia, yesterday was 42 degrees C, (107f).

Thanks, Id appreciate any advice.

Michael.

98yota

First I would check your grounds, make sure they are all connected and clean. CDI or coil could also be bad. I'll have to a little digging to find the test procedures and specs.

__________________
1993 Yamaha WaveBlaster 701
1989 Yamaha WaveJammer 500

Michael1973

Today ive cut the ignition leads back 1/4inch and screwed the caps back on. Cleaned the 4 slightly rusted earth terminals on the coil in the rear box, ran an extra earth from the back coil earths direct to the battery, cleaned the main earth on the block, vaacuumed the magneto housing clean and inspected to make sure, reinstalled mag cover, removed each of the 6 pins on the mag cover and the connector and recrimped and inspected and made sure they were gripping their opposite pin, did the same in the rear box connector, there was a little bit of corrosion but im confident I cleaned them all up right, tested the coil, primary side 0.7ohms, lead side 23.0ohms, tested for continuity on the rear box wiring, pulled the connectors apart at the mpem, crimped the terminals down a little to make sure they were tight, battery was charging while I had other things disconnected. Still no spark, and still no signal down the white wire to the coil. Ive checked real close to make sure there is no tiny spark even.

Id like to know how to test the output of the trigger in the mag cover.

Otherwise Im left with the mpem, the cdi is built in to the mpem, its not a seperate unit like earlier doo's.

Any advice would be great!

Thanks.

Michael1973

To try and test the trigger coil in the magneto housing, I probed those wires back at the mpem (yellow/white and black/yellow), my multimeter isnt very fast at grabbing readings, its digital also, but when I turn the motor by hand the meter will definetely measure a very small voltage maybe 0.2v sometimes it will jump higher but its only a cheap meter. It jumps all over the place when the starter turns the engine also.

Michael1973

I wish I had access to another mpem without buying it, althou its the number one suspect (lol). Ive opened the mpem, Ive attached a pic, I figure I cant make it any worse, any idea where to test/check? Im trying to follow the circut from the trigger inputs the to the coil output wire (white), surprisingly it still works, without spark. Thanks for your help.

Attached Thumbnails

 

Michael1973

I had a brainwave today and check the rpm on the dash while cranking, and was cranking at about 500rpm, so the mpem is getting signal, just not putting it out.

98yota

here is a link that might be help:

MPEM Ignition Module Test Data

__________________
1993 Yamaha WaveBlaster 701
1989 Yamaha WaveJammer 500

Michael1973

Thats great info, but isnt specific to my mpem, the color codes dont match. Thanks anyhow.

98yota

No problem, I'll keep digging.

__________________
1993 Yamaha WaveBlaster 701
1989 Yamaha WaveJammer 500

Michael1973

Any luck 98yota?