Ok I am at a loss, bought a 97 seadoo xp 787 last year and it ran great until the last time out at the end of the season. When you would get to 40 mph it would still accelerate but would miss like it was hitting the rev limiter. Well had full bore go through the engine, new wear plate and the impeller looked good, all new fuel lines rebuilt carbs, and new fuel filter and guess what, it still does it. And now to add to it going across the water at about 40 it will just die at times out of knowhere. If you crank on it for 5 to 10 seconds it will start. Sometimes when it restarts it runs fine sometimes it acts like it is running on one cylinder and then when you take off the other one picks up and it runs fine, until it decides it wants to die again. Please help.
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I had a very similar problem to what you are describing. It turned out to be the rectifier/voltage regulator. To test if that's the problem, disconnect the red lead from the rectifier. This will disable charging of the battery so be sure you have a fully charged battery when you do this.
The rectifier is in the front E-Box next to the MPEM. Here's what it looks like.
Lou
The rectifier is in the front E-Box next to the MPEM. Here's what it looks like.
Lou
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And maybe I need to go a plug hotter, maybe it is fouling the plug out causing it to die, but it doesn't explain the stumble. It is weird full throttle up to 40 it is fine, above that it like jerks it keeps pulling good and found if you trim the front down it doesn't do it nearly as bad. End of season last year I got a big rock stuck in the cone after it had started doing this stumble thing and it quit, got the rock out and it started doing it again
i would try a rectifier as lou suggested, he just had a sinilar problem with his ski, but get compression tested, spend 5.00 on 2 new spark plugs, gap them proper, and run the proper amount of oil after break in period, here is that video on checking rotary valve timing, missing is one thing, but backfiring, suggests a timing issue http://www.youtube.com/watch?v=ULL5gfQs_UA
I'm going with a pump problem here. Wear ring crossed my mind, then he admitted to the rock incident. I have had a rectifier do this to me recently. However it more often has been a chunk of the old dry wear ring busting off and allowing the ski to ping the limiter throughout the rpm range. The rock could have damaged the impeller also of coarse. I'm just sayin' I wanted to offer the pump as a suspect here.
Pulled plugs and they are soaked in oil, got a good compression tester and both cylinders were at 151, with these plugs looking fouled should I try one step hotter during break in? They have a total of about 2 hours on them and they look like they are a year old. I ran on one set of plugs last year and they never fouled out
Ok finally got the ski back out and ran it, no longer dies with the new plugs. Unhooked the rectifier and it still acted like it hit the rev limiter, but here is what I found out. Taking off if you mash it it hits the rev limiter for about 3 seconds, if you keep it held wide open for the whole time at 45 it acts like it hits the limiter once you get to 55 it keeps doing it but if you let off the throttle a little bit it goes away. Also if you angle the jet down it doesn't do it nearly as bad or if you are cornering it doesn't do it. Is it possible the impeller is not enough for the ski. It has r&d intake and nozzle. Also has a butchs head and r&d exhaust. It has always hit the limiter when taking off and everyone says it shouldn't if it is a bad prop which one should I get? I would like it to go faster
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