MPEM bypass

[chariotdriver]

This should be fun and I'm not sure if it's legal, but here goes.

I loaned my skis out and when they came back after a few days the 96 GSX has a hole burned in the MPEM and won't work. Something shorted out and the folks replaced the 5A fuse with a 15A fuse; what the heck! Traced the short to the single purple wire going into the brain box then swapped the whole MPEM with the one from the 97 and it ran fine. Now I find out how much they cost plus reprogramming and I'm thinking "not so much."

My question is what is required to bypass the MPEM? I know I need a white wire from the ignition module to the coil to make it spark and the yellow runs the starter solenoid and timing comes from the front via the magneto system. I'd like to run the start stop switch for just a start function and use the DESS key (with a shunt inside) to close the relay to power everything. What all does the ignition module get from the MPEM besides power? Does the ignition module have a brain which needs to be unlocked as well? I know the gauges, beeper, etc won't work but the boat is getting pretty old to be dumping a bunch of coin into it.

thanks for any help, cd

 

[seadoosnipe]

And I thought I was shade tree!

Unreal......someone in here that thinks like me. Unfortunately, I don't think you can bypass it. I'd find the knuckle head that put in that 15 amp fuse and put a knocking on his head!

The mpem's purpose is to receive and interpret information, distributes that information, start/stop functions (controls the igniton), the DESS, and the engine rev limiter.

In some models, the ignition system and rectifier are built into the mpem, in others, it's seperate.

 

[derek]

sorry dude. the MPEM IS the ignition module. it does spark, rev limit, spark advance. it also does the anti-theft. and adds in guages and misc stuff. you can't bypass it.

 

[chariotdriver]

Complex solution

It can be done!----sort of. One of my buddies is the 100# brain type who works on those expensive aircraft parts, etc.

He hooked up an oscilloscope and spectrum analyzer between the MPEM, CDI and Rectifier; here is what we got.

The MPEM and rectifier do not talk, the rectifier just sends 12 volts to the MPEM through the MPEM 15A fuse and from there it goes to charge the battery and power everything else. The wires from the magneto (really a 3 phase generator) go directly to the rectifier.

The CDI talks directly to the coil for spark production (white wire) and gets the engine index directly from one of the coils in the magneto assembly but it's not one of the yellow ones which provide power.

The MPEM and CDI have 4 wires between them. One is 5A of power for the CDI, one is an ignition impulse which is a one way circuit from the CDI "to" the MPEM used for RPM on the tach and the rev limiter. One is a rev limiter link (do we really need this and the other is the timing advance curve.

MSD makes a rev limiter/advance curve box for about 100 bucks so I'm gonna run this rig w/o an MPEM.

The final plan will require removing the DESS to stop the engine and you will be able to grind the starter with the start button if the engine is running.

It seems such a shame to have bullet-proof motor which is soo simple and reliable only to fall to the digital weak link.

This is how a 96 GSX is set up, (3 seperate boxes) I know the more recent boats have more of the stuff built into one potted board.

hope this helps, cd

 

[ILLNESS]

sounds like a headache.. id just find a nice used MPEM and call it a day..

 

[chariotdriver]

You're right

Found a used MPEM on ebay; should be here in a few days. The by-pass worked just didn't have any VTS, gauges, beeps, start/STOP, etc. It was like the old lawn mower when I was a kid; rope start, throttle, and had to use a screwdriver to short the plug out to get it to stop. The MPEM has a DESS but do I still need to go to the dealer and get the timing synched? I read it in the shop manual somewhere. thanx, cd

 

[JESSECONSOPOLUS]

Worth It?

dosent seem worth it man. sounds like a headache............

 

[kustomkarl]

Found a used MPEM on ebay; should be here in a few days. The by-pass worked just didn't have any VTS, gauges, beeps, start/STOP, etc. It was like the old lawn mower when I was a kid; rope start, throttle, and had to use a screwdriver to short the plug out to get it to stop. The MPEM has a DESS but do I still need to go to the dealer and get the timing synched? I read it in the shop manual somewhere. thanx, cd

The Seadoo Dealer is the only place to get the DESS programed to the MPEM.

Karl

 

[JESSECONSOPOLUS]

ya too bad u dont live around here, what i hear most dealers will rip u a new one. our dealer here actually programs the key for free if u buy it from him, otherwise its like 20 bucks if u have ur own. everyone else is usually like 70 bucks when u step in the door, eh' karl?

 

[scooper77515]

I guess I found the one decent guy...he programmed mine for free, and I bought it at a different store!!!

 

[JESSECONSOPOLUS]

ya man its cool to find good dealers like that, there arent to many left it seems......

 

[scot750]

I Have Used Several Of The Aftermarket Ones And They Come With Or Without Dess. I Can Get You One Send Me A Message If You Need It.
Scot