Minty 1994 GTS

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Picked up this 1994 GTS yesterday. I’ve never seen an early model this clean. It’s 100% aesthetically. One owner, very well taken care of. Fuel lines have been changed out, with the exception of the vent lines. It still has the original cartridge fuel filter and I believe it has the old mineral oil in the oil reservoir. It cranks right up, and I ran it yesterday for about 20 mins and it started some surging and bogging business. Today I changed the plugs (BR7ES .020 gap) and cleaned out the cartridge fuel filter. Took it for a spin and got about 20 mins out of it, and it started surging. I pulled it out, swapped out to an in-line fuel filter and ran it with myself and the wife for about 20 mins. No issues. I dropped her off at the house and I kept going for another 10-15 mins and didn’t have any issues.

When I cleaned out the cartridge filter the first time I noticed some garbage, small sediment stuff in there. I cleaned out the bowl with some carburetor cleaner and then put the filter element in the bowl and swirled and shook some marvel oil around in it and re-installed it. After a second try it ran again for about 20 mins (with new plugs) and started it again. Then I swapped over to the in-line filter. Again, the old bowl had some sediment and garbage floating around. After I swapped to the in-line I also added some new, fresh ethanol free fuel and it ran fine for as long as I ran it that time. I complete realize that the carb may be in need of a rebuild. Just throwing all this out there for some advice from others with similar experiences.

I guess I get kind of perplexed by the fact that it runs perfect for 15-30 mins before acting up. I do realize the fuel delivery may be getting clogged by old junk in the bottom of the tank, but I don’t know. I’m gonna try to get through this tank (less than 1/2) and then pull it out and flush it out. What should I flush it out with?


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You really are risking damaging that pristine ski’s engine.

Clean the tank out, don’t add any inline filters, replace the fuel selector and rebuild the carbs with only genuine Mikuni parts. Then ride the paint off that minty fresh Seadoo.
The ski really does look great! Congrats!

As far as the surging goes, I think I would go ahead and replace that fuel selector, as well as the o-ring on the filter. You’ll also want to go through the carbs with Genuine Mikuni kits. It really needs to be done on any new to you ski, even if it looks mint...

You’ll also want to go ahead and drain and refill the oil if you think it’s been sitting for that long. The mineral oil is fine, but it does have a shelf life...
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