Please HELP!!!

[IDoSeaDoo]

You can actually remove the two screws holding the oil pump and use a drill to spin it. If you have the carbs off, you'll actually see the oil squirting out of the little injectors pressed into the intake ports.that's the sure-fire way to test it. You should see both injectors pumping out the same amt. of oil.

 

[KyleB]

Anyone that has been following this thread knows I have been frustrated and confused about trying to get this ski back in the water. Today I think I may have heard it all. I called the local SeaDoo sales service shop in town because I have pretty much given up and was told they don't work on anything that old! Huh? What the....! I figured a service group would be in the business to make money especially in this day and age but I guess this outfit has all the business they want. Anyway, the fellow that I spoke to was nice enough and he is just probably following the direction of the owners. He told me that it sounded like to him the MPEM has gone out after only briefly describing the problem to him. This don't sound right to me which is where you guys that knows these boats like the back of your hand comes in. Is there a check I can do to verify the MPEM is working correctly? When I press the starter button 5 times without the DESS connected the system lights up for 33 seconds then shuts off. From what I understand this is a self diagnostic mode the MPEM goes through and is normal.

Also, one other development. the unit is idling beautifully but when I start to apply throttle she dies. When I remove the return fuel line the system is dry. I would think that fuel would be in the line when I do this. I assumed that fuel would drip out of either the supply side or the return side but it doesn't...just dry. I don't see where fuel is leaking anywhere but my thought is that maybe I have a small hole somewhere in either a connection or in the line itself. I know from other small engine work that if you have a small hole in the line the engine will suck air instead of fuel the the demand increases and cause the engine to die...just like what I have. Question. Will I see fuel leaking or will some holes be so small that you may or may not see fuel on the line? I'm thinking about changing out all the lines eventhough they grey lines have long been removed and putting new lines and clamps on.

What is the collective wisdom of the group? Is the MPEM answer logical? Why do I even need all that garbage on the ski? Has anyone ever bypassed the electronic "brain" and just built a ski that is basic? I realize that I would loose any theft deterrent features and perhaps some of the other sensors but the fuel, oil, and combustion all appear to be mechanical.

Any help with this solving this mystery would be very much appreciated and while I'm thinking of it I really do appreciate all the help I have gotten so far.

Kyle

 

[ski-d00]

most shops won't work on a 96xp, they are only worth about a $1k and their bill would be $500 or $700 so it doesn't make sense and the customers will end up furious. your MPEM is fine, you talked to somebody who doesn't know what they are talking about. you can't bypass the MPEM(not without replacing it with something similar), it's not just a theft deterrent system, it advances the timing with a timing curve.

here's what I think happened, somebody replaced the motor with an SBT and didn't rebuild/clean the carbs so it ran lean and cooked a piston. just because it will idle doesn't mean that it will run at higher rpms and make power, it will run on 1 cyl suprisingly well which is basically what yours is doing. I doubt you have any sort of fuel leak, that is not common on seadoos and the lines will appear dry, that's normal. you need to rebuild the top end and yes, you should check your oil system but I doubt it is clogged and is probably working fine.

it will not run well at higher rpms with that compression, it's time to fix it right and you can do it yourself for about $300, with our help.



have you been using full synthetic xps oil? if not, that would be the other reason a piston went down.

 

[IDoSeaDoo]

The MPEM is the brain, it's what controls ignition timing. You can (and would be better off) replace it with an MSD ignition module for about ~$320. This problem could be caused by a bad computer, but it's not likely. MPEM problems tend to be either all or nothing (in my experience).

Now, since you pulled off the return line and found it to be dry is a great lead. When I pull my ret. line off and crank it, it spurts out fuel like a dog onto a hydrant. You definitely have a fuel delivery problem. I wouldn't replace all hoses unless they're really brittle. I'd just cut the last .5 inches off and reclamp them. Having a hole in a fuel hose will give you all sorts of problems, I just had one EXACTLY like that, though mine wasn't major, just annoying. Go thru all the hoses and make sure all your clamps are tight. I forgot if you've rebuilt the carbs or when you did, but you could have clogged internal filters. Check your pulse line both at the block and at the carb, make sure it's not cracked. Make sure you're working with good compression as that is what gives you the vacuum that creates that pulse. If you recently replaced pistons, I hope you made sure that the arrow was pointing at the exhaust manifold (I don't think it would run at all otherwise, but idk). Hope this helps, got to get back to work

 

[KyleB]

most shops won't work on a 96xp, they are only worth about a $1k and their bill would be $500 or $700 so it doesn't make sense and the customers will end up furious. your MPEM is fine, you talked to somebody who doesn't know what they are talking about. you can't bypass the MPEM(not without replacing it with something similar), it's not just a theft deterrent system, it advances the timing with a timing curve.

here's what I think happened, somebody replaced the motor with an SBT and didn't rebuild/clean the carbs so it ran lean and cooked a piston. just because it will idle doesn't mean that it will run at higher rpms and make power, it will run on 1 cyl suprisingly well which is basically what yours is doing. I doubt you have any sort of fuel leak, that is not common on seadoos and the lines will appear dry, that's normal. you need to rebuild the top end and yes, you should check your oil system but I doubt it is clogged and is probably working fine.

it will not run well at higher rpms with that compression, it's time to fix it right and you can do it yourself for about $300, with our help.



have you been using full synthetic xps oil? if not, that would be the other reason a piston went down.

Thank you so much for the reply ski-D00. When he told me that about the MPEM that exactly what I was thinking...this guy don't know jack! Anyway, I realize that if I replace the MPEM I would need to replace it with another module that would basically do the same job. I'm just glad that you don't think I need to do that right now. As far as oil is concerned the previous owner used synthetic and I have since only put synthetic in it. I think you are right. I think it needs a top end job but what still bothers me is the fact that it cuts out when ever you try to apply throttle. This is looking like more and more to be a fall/winter project and the kids will just have to understand. Thanks again.

Kyle

 

[KyleB]

The MPEM is the brain, it's what controls ignition timing. You can (and would be better off) replace it with an MSD ignition module for about ~$320. This problem could be caused by a bad computer, but it's not likely. MPEM problems tend to be either all or nothing (in my experience).

Now, since you pulled off the return line and found it to be dry is a great lead. When I pull my ret. line off and crank it, it spurts out fuel like a dog onto a hydrant. You definitely have a fuel delivery problem. I wouldn't replace all hoses unless they're really brittle. I'd just cut the last .5 inches off and reclamp them. Having a hole in a fuel hose will give you all sorts of problems, I just had one EXACTLY like that, though mine wasn't major, just annoying. Go thru all the hoses and make sure all your clamps are tight. I forgot if you've rebuilt the carbs or when you did, but you could have clogged internal filters. Check your pulse line both at the block and at the carb, make sure it's not cracked. Make sure you're working with good compression as that is what gives you the vacuum that creates that pulse. If you recently replaced pistons, I hope you made sure that the arrow was pointing at the exhaust manifold (I don't think it would run at all otherwise, but idk). Hope this helps, got to get back to work

Thank you IDoSeaDoo for your reply. I recently rebuilt the carbs when this problem first started so all parts are clean in that regard. The compression on the MAG cylinder is low but (125PSI) while the PTO is 140. Do you think that is my problem and why it dies after applying throttle? I know I need a top end job but I was just hoping I could get it fixed good enough for the kids to ride some this summer. I was planning on doing a top end job this fall. I'll just have to tell them in the words of the famous philosopher Mick Jagger "you can't always get what cha wanted". At least we have the big boat and they can wake board and ski. Thanks again.

Kyle

 

[KyleB]

By the way, do either one of you guys know a good tutorial on doing a top end job on this thing? Thanks.

Kyle

 

[KyleB]

Ok so when I got home this evening from work I decided to go ahead and start the top end rebuild. I pulled the head and got the pistons exposed. I plan on taking pictures so I can document this effort and hope to post them at some point but the bottom line is that the MAG piston was burnt and crusted over pretty bad. The cylinder dome is pretty scored also. Will I need to either get that re-ground or will it be ok? I honestly could not believe how bad this piston looked. No wonder she was not running! Anyway, I am leaving the engine in the boat for this rebuild because it seems I can get to all components that I need to get to. Does anyone disagree? Another question that I have is whether or not I need to get an over bore piston set? This is an SBT rebuild so if I call and give them the number of the head will they be able to look it up and tell me what I need? Lastly, will I need to do anything special to the bottom end of the engine while I'm doing this? Thanks again for everyones help.

Kyle

 

[ski-d00]

Yes, you will need two new oversized pistons if you want to do it right and you will need a qualified 2 stroke machine shop to bore the cylinders. I would plan on sending them out as you may not have a good local one. Should cost about $40/cyl plus shipping both ways, plan on a hundred or so.

You can leave the motor in the ski, no problem. SBT motors are either .5mm over or 1mm over usually. Using calipers you can measure your bore easy enough. You will probably want to go another .5mm over if there is even slight scoring in the cyl to make sure it cleans up. 1.5mm over is fine. The head dome area should clean up fine but don't grind on it, just clean it. you should post pics that will help us.

nothing special needed for the bottom end, you can pack a clean rag in there to keep the rod from hitting the side of the case and put clean rags over it so nothing falls in.

 

[KyleB]

Ok I'm trying to put up some pictures of the dome and piston comparison but can't figure out how. Man oh man after struggling with this XP for 3 weeks and now I can't figure out to put pictures on here I'm starting to get a complex! I searched in the FAQ but the add albums link was not there. Anyone, know how to do this? Thanks.

Kyle

 

[KyleB]

Don't feel so bad after all. I figured it out. Anyway, you can see from these pictures what I'm dealing with. I checked the cylinders and honestly they feel and look great. I didn't see any scoring at all.

So what do you guys think cause this? My guess is detonation from operating too lean. What say ya'll. Thanks.

Kyle