1999 GTX LTD Mpem

[andrew_k83]

Anyone have a mpem for sale for a 1999 GTX Limited? Carb model. Part number should be 278 001 398.

The seadoo dies intermittently, frequently at idle and sometimes at full throttle. Sometimes it will fire right back up, other times I need to take the key off then put it back on and fire it up. Sometimes the gauges go blank, other times they stay on.

Could be multiple issues. DESS post and key were just replaced but did not solve the issue so I’m leaning towards mpem. Motor runs great when it stays on. When it dies, it’s sudden and doesn’t bog at all.

Any opinions or any mpems for sale?

Thanks in advance!

 

[Ckrawiec]

Just out of curiosity...why do you suspect the mpem?

You said the ski starts and runs but dies......the mpem is seeing everything it needs to get her going.....I'd be looking more closely at:
1) are you losing fuel delivery?
2) are you losing spark to the plugs?
3) your issues sound "electrical" in nature and just blindly replacing the mpem may not get you there

a 20 year old ski needs a lot of attention to stay in good working order.....

 

[Ckrawiec]

Just out of curiosity...why do you suspect the mpem?

You said the ski starts and runs but dies......the mpem is seeing everything it needs to get her going.....I'd be looking more closely at:
1) are you losing fuel delivery?
2) are you losing spark to the plugs?
3) your issues sound "electrical" in nature and just blindly replacing the mpem may not get you there

a 20 year old ski needs a lot of attention to stay in good working order.....

Just another thought......the Start/Stop button is a mechanical switch (normally open)...so if the machine shuts down suddenly...I'd conjecture that the ski thinks the button was pressed...the S/S button has been known to fail as well, or be intermittent...just something else to consider

 

[andrew_k83]

Just out of curiosity...why do you suspect the mpem?

You said the ski starts and runs but dies......the mpem is seeing everything it needs to get her going.....I'd be looking more closely at:
1) are you losing fuel delivery?
2) are you losing spark to the plugs?
3) your issues sound "electrical" in nature and just blindly replacing the mpem may not get you there

a 20 year old ski needs a lot of attention to stay in good working order.....

I’ve checked on those issues as well and this is where I ended up. The mechanic who programmed the new key told me his next step would be to replace the mpem if the key did not solve it. I’m not experienced by any means with these though, so if you any other suggestions on what I could check I’ll definitely look into those! And maybe revisited fuel/spark... again lol. Thanks for the quick reply

 

[andrew_k83]

Just another thought......the Start/Stop button is a mechanical switch (normally open)...so if the machine shuts down suddenly...I'd conjecture that the ski thinks the button was pressed...the S/S button has been known to fail as well, or be intermittent...just something else to consider

I hadn’t thought of that. You know a good way to test it, or would I just need to replace?

 

[Ckrawiec]

I hadn’t thought of that. You know a good way to test it, or would I just need to replace?

Its just a two wire switch, so putting a meter on it and testing the resistance change will tell you if its working...but if its intermittent, they are not that expensive to replace...way less than an mpem.

ALWAYS start checking with the "free" stuff first (wiring connections, continuity, fuses, etc)....working towards the more costly items up the money scale.....the ski starts, so I'd consider the mpem last (that's not a cheap item).

 

[Ckrawiec]

Does your ski have a CDI ignition module? My '96 ski says it has one but it CDI was incorporated into the mpem....if you have a faulty ignition module, you could be losing spark to the engine and she'd shut down.

 

[mikidymac]

Just had the same issue on a 1997 XP. Riding it would just go dead as if puling the lanyard. Replaced the DESS post with a new one last year everything was good to go.
FIrst ride of the season, back to the exact same thing. My cousin sent the MPEM to Jess at Westside powersports and everything checked out. Got it back and noticed the MPEM plugs had some corrosion on them so I cleaned them really good with DeoxIt spray then di-electric grease and it worked flawlessly all weekend.

 

[mikidymac]

Does your ski have a CDI ignition module? My '96 ski says it has one but it CDI was incorporated into the mpem....if you have a faulty ignition module, you could be losing spark to the engine and she'd shut down.

1999 GTX has the integrated MPEM.

 

[Ckrawiec]

1999 GTX has the integrated MPEM.

Was the separate CDI module phased out altogether at some point and incorporated into the MPEM universally????

 

[mikidymac]

Around 1997 I want to say.

 

[andrew_k83]

Its just a two wire switch, so putting a meter on it and testing the resistance change will tell you if its working...but if its intermittent, they are not that expensive to replace...way less than an mpem.

ALWAYS start checking with the "free" stuff first (wiring connections, continuity, fuses, etc)....working towards the more costly items up the money scale.....the ski starts, so I'd consider the mpem last (that's not a cheap item).

That’s what I’ve been trying, definitely possible that I’m missing things along the way given my almost zero experience with working on these things.

I’ll check on the switch - thanks for the info

 

[andrew_k83]

Just had the same issue on a 1997 XP. Riding it would just go dead as if puling the lanyard. Replaced the DESS post with a new one last year everything was good to go.
FIrst ride of the season, back to the exact same thing. My cousin sent the MPEM to Jess at Westside powersports and everything checked out. Got it back and noticed the MPEM plugs had some corrosion on them so I cleaned them really good with DeoxIt spray then di-electric grease and it worked flawlessly all weekend.

I was hoping that would be my fix too, but everything looks spotless. I may try cleaning again just to be sure.

 

[etemplet]

These issues are what I am encountering on my 1996 XP. I'm gonna add checking the start/stop switch to my list. I agree.... check the "free stufff" first. !

 

[Ckrawiec]

I had a thought this morning.....checking things on the trailer on dry land is WAY different than the actual conditions you are encountering on the water, SO always keep that in mind as well....on the water the ski is bouncing around and things like a mechanical switch could show up and test perfectly good in a static situation but behave very differently under actual USE conditions......THAT just adds a whole new level of complexity to sorting some of the ski's maladies out.....but keep at her.

 

[andrew_k83]

Update for all who helped out -

I ran through the entire ski again in the driveway. Electrical connections, fuses, spark plugs, fuel lines, etc. I replaced the spark plugs just for good measure and found the vent line from the fuel tank that splits to the two relief valves was plugged up.

Replaced the line and cleaned out the check valves and the ski ran great today. Didn’t die once. We’ll see if it keeps that way. I’m assuming the vent line being plugged up threw the fuel pressure off enough to cause it to die intermittently. Not 100% sure since I checked a bunch of things though. Definitely solid advice on checking the “free” stuff first.