Rough runs after supercharger rebuild


I have a 2004 Seadoo GTX and before anyone says “just go buy a new jetski” let me say this thing is super clean and when I purchased it 4 years ago it would top out at 70 mph. Then each year I lost 2-3 MPH. So at the end of last season after only reaching 63 mph on flat water I decided I better get this SC rebuilt. 2 weeks ago I sent in my supercharger and of course the staff did an awesome job getting this rebuilt in 24 hours and getting it right back to me. However, after installing it I have had nothing but troubles! I have new plugs, oil filter, oil, and fresh antifreeze. First time out, RPMs are hitting 5000 - 6000 and I’m only going 12 mph. Check all fluids and it looks like my oil is too full. Pull out a quart. Take it out a week later and same thing. At idle speed it will bog down and stall. When it does go, I can’t get it above 42 mph! Wear ring does not look to be damaged but I have no removed it either. Just seems ironic that at the end of the season I had no issues other than only reaching 63 and now, after SC rebuild, I can barely keep it running and never go over 42.
Anyone have any thoughts?? I’m going back out right now to remove all the oil and try again. I will also double check the plug gaps.
Thanks in advance for any insight you can offer!



Sounds like you definitely have a wear ring or impeller issue based your symptoms. Too much oil will rob you of hundreds of RPM, not thousands.

Make sure your clearances are right with the wear ring and that your impeller is not damaged or have any other issues with the pump


I’ll check it but it just seems too coincidental.
If I try to go into reverse it bogs down and barely stays running. I’m going to pull the SC out again today.


Honestly sounds like a pump issue, but let us know what you find when you pull it.


Still going to take the SC back out but forgot to update this mornings adventure. Took more oil out so right now it is below half. Double checked spark plug gaps and ensured they were at .30. Went back out and still same issues.
OOPS!!! Rushed to get out of dock area, didn’t strap it down. Jetski comes off trailer on the on ramp to highway! Luckily because I was blocking the road drivers had no choice but to help pick it up and put it back! All’s good, no damage other than a trailer light. Lol.
What an adventure this summer is becoming. :slight_smile:


I am guessing that you were going by the speedo as far as how fast it was going originally correct ? Then you noticed it going by the speedo slightly slower by only a K or two at a time ?
Did you think about checking out the speedo wheel or sensor to check it was not the problem before all the BS you went through ?
Did you bother to get them to check your pump first as why would you touch the SC ? Did some great friend give you that advice or did some one in a Forum tell you to spend bucket loads on something you didn’t even know was the problem ?
Doing your own work is a great way to either spend a sht load of extra money and plenty of down time and lots of fun like you are now having, was worth the savings right :wink:
If you would have taken it in for a few hundred dollar service they would have checked everything changed the oil and filter and made sure the levels were right and then they would have told you this and that are wearing and may need attention soon.
Instead with no expertise you made a ski that was working great just by your perception was a little slower by the speedo, you didn’t mention if it was slower by a proper GPS test ?
Keep up the great work as you can end up with something eventually that won’t do anything but float hopefully :wink:
Keep asking other amateurs in a Forum for advice and that is what will end up happening, get it to a professional and get it doen properly as what you are doing is just making it worse and a seized engine or blown engine is more than likely your end result, you don’t have the expertise nor do the people on a Forum with how much information you gave as we can all just keep telling you this or that and a worn pump will lose you a couple k top speed as well as a similar effect as a slipping clutch on a car when you are trying to take off fast, it’s called cavitation from to much space between the wear ring and Impeller, it won’t drop you thousands of RPM’s not that quickly unless the wear ring fell out lol.
I know my response may sound a little gruff but from your original post and secondary responses that is the only useful response any one should have given you, a few hundred dollars saving has now cost you a lot of time and frustration and an unnecessary SC rebuild, as a SC normally doesn’t slowly lower boost unless there is a leak and unless you had a service History from the Ski that told you it was time for an SC rebuild as they last about 800 hours of normal use before needing to be serviced.
Any way I am sure most will make some form of dumb response to my comment as most on these forums think self service is the way to go and I mostly see people that follow that advice end up like you, with a SKi that was just needing a proper service and ends up barely running, great job :wink:


Wow. Thanks for your feedback. Where do I begin. First let me preface this by saying I live in a shitty little are with a population of less than 30k people so finding qualified PWC mechanics is a joke. When I did reach out to so called professionals they don’t want to touch a 2004 machine. Next, I’ve owned this ski for 4 years and have never changed the SC and the guy I bought it from said he never changed it and didn’t know if the guy he bought it from 2 years prior had it changed. So I am banking on the fact that it has at least 800 hours on it and it is 6-8 years old minimum. With that in mind I ventured on the journey to get it rebuilt.
No it is not the speed wheel or sensor because I changed that last year when I broke the original.
No I didn’t check the pump first, because prior to pulling the SC and sending it in for rebuild the ski ran great minus 7 MPH. No it barely stays at an idle without stalling.
Also why would I pay someone $200 to do an oil change and spark plugs on a jetski??!! My 16 year old daughter can change the oil and plugs on a ski but hopefully not over fill it. LOL.
No I didn’t do a proper GPS test. I ride this thing 2-3 times a week so I know when the speed is off. because not only do I have a speedometer that works I also have another jetski that only tops out at 55 and now it goes faster than this one.
Although I appreciate any response I get in this forum I have to wonder why you would respond? I mean you clearly think everyone on forums is an idiot, yet here you are trolling about! :wink:

I’m going to keep searching for a professional shop I guess even if it means driving to another state. I do know that I have a “maintenance” notification on the dash too so I suppose I better get it looked at or unload it.


This is the main problem with people thinking a service is just oil and filter lol, yes any fool should be able to do this but it seems some can’t and over fill or under fill so it must be harder than you thought :wink:
Maintenance/Service means they check things that need to be checked and then let you know and tell you how much ot will cost to change, you also get a warranty when they do it rather than if you do.
If you read through these forums and see how many people have trouble after their expertise fails as you all think it’s so easy as why on Earth would anyone need to do an apprenticeship or train to work on small engines and the Electronics that go with them.
I am an expert in my fields and would never go onto a Forum that has to do with repairing Electronics that I do with the proper equipment and in clean rooms, no expert will tell someone to do it themselves as the amount of tools needed for most post 2000 vehicles is not just a Screwdriver and Shifter.
Did you have any equipment to connect to your Computer system to see if it was running as it should, if the injectors were working correctly as you may not have re-connected the fuel system correctly and end up with insufficient fuel and this could also cause lower revs and less power, dirty fuel and fuel injectors getting clogged slowly over time causing a couple K slow down per year ?
Fuel filters, fuel lines, air leaks, pressure tests, I could go on about all the hundreds of simple things a non expert could cause without even knowing and to not even be able to test anything other than put it together and take it for a ride lol.
What you need to do is have a look in a Jet Ski workshop one day and see all the equipment and how they test a Ski to see what could be wrong and then you may understand why I make the comments I do about self service. Your saving of the couple hundred dollars didn’t really save you anything now did it :slight_smile:Maybe Pray for it next time as it at least would have kept going and did you read the hour meter to see how many hours it had done rather than say how old it was :slight_smile: My 2008 SC 1800 Yamaha has only done 310 hours as we have a few Skis, I wouldn’t have bought a Ski if I couldn’t afford to look after it, would you do your own servicing on your Vehicle ?
I have the expertise to be able to do everything required on a new Vehicle let alone a 10 + year old Ski, trouble is expertise doesn’t equate to having the equipment to do it, the cost of a Maptuner X isn’t that much about $400 and the License for your Ski only another $500 and at least you can Tune your Ski.
Just curious besides the thought that the Ski was old how did you determine the SC needed to be refurbished ?
People never like facts or being told just how not great they are at some things and when they stuff up its always everyones fault other then theirs.
I take my items in to a professional as then not only do I get it back the same or next day but I know I won’t have to swim back to shore because I made a mistake, I also know if the Ski sinks or my Vehicles burst into flame my Insurance will pay me out to replace the item, if I did it myself with out the certifications to be qualified then I threw my money away, also if some one was hurt. like say your 16 year old daughter riding the Ski and it blew up or sank while she was way out or it wouldn’t stop and went flat out and ran her into a pilon or another boat, how much would the $200 saving be worth then.
Any way my two cents , eventually everyone either trieds to pass off their self worked item onto some other poor sucker or they take it to an expert and try to BS that it’s how they bought it rather then say yes I did this to save money ROFL, call me a troll if you like but it was you that did your Ski not me and I never gave you bad advice to do it yourself so blame the others that did and listen to sense next time :wink:


Well I’m sorry that you have so much time on your hands that you can troll on forums offering no help but to tell people they should take their equipment to a professional. See you are missing the point of a forum! They are here because people like to be self sufficient and/or take pleasure in learning and the satisfaction of a job well done when they succeed! This is obviously something you know nothing about. See you are the percentage of people that think failure is something to be afraid of and that it should be avoided at all costs. Me, I see failure as a learning experience and a way to grow personally. I’m not afraid of failure because I see the importance of re-evaluating every failed situation and how I can take what I’ve learned and apply it to life. Forums are for those of us who want to try and whether we fail or succeed we provide feedback on such forums to help others. Maybe if you could keep your personally feelings to yourself and offer some real advice such as; “yes, I’ve done the same thing and here is what worked for me” or “I am a marine mechanic and this is what I would check next” but to sit back and say in a 600 word essay that “I am not qualified and you should take your ski to a professional” is offering no help what so ever. So please do us all a favor and do something else with your spare time!


So I finally got to pulling the SC out again. Everything looked fine but as I was reinstalling I realized that maybe last time when I installed the SC after rebuild I may not have connected the exhaust pipe all the way. When I removed the exhaust it was tight as could be in fact I had a hard time even getting unclamped. When it was attached after the rebuild it seemed a little loose but I continued anyway. This time, I pulled it all the way in place and when the clamp went on it was tight like before. So I am not sure if that would have an impact or not. Anyway, I also pulled the jet pump. Attached are a couple of pics of both the inside of the motor where the SC connects and also of the wear ring. Please let me know your thoughts on the pics. I’ll be dropping it in the lake today to test.


Wear ring has seen better days but hard to tell the clearance by that angle. Basically max is height of a dime.

And an exhaust leak can rob tons of power as you’re essentially choking the engine.


So after testing the ski last night it performed almost as it should. Speeds were still a little off at around 55-60 mph. I’ll blame that on the wear ring and get that changed out. So it is quite obvious that the exhaust was the real reason it was performing so badly.
Now on to the reverse issue. When the reverse gate is pulled from the ski, the reverse cable works as normal going in and out with each pull. Soon as the gate is reattached it will not go into reverse nor will the cable pull it back out of reverse if I manually moved. Nut doesn’t look damaged but I’ll replace that as it appears to be the common reason.