I have 2 identical 1994 SEA-DOO SPX's. I ran them for a week at lake of the Ozarks in Missouri. They both ran generally great, however one of them experienced an issue twice during that time. . All of a sudden the one would cut out at full throttle. After sitting for the day it ran fine again. If I let off the throttle it would keep running. If I kept the throttle wide open it would die.
It would always start an idle fine. It acted like it just couldn't get any gas at times. If I would "pump the finger throttle" when this was happening, I could get it to get some gas and pick back up. I got gas from the same marina all week. I check the fuel filter and it seemed pretty clean to me. There was a small amount of black grime or sludge in the bottom fuel filter, but not much. When it was having this problem, It would only go 3-5 seconds at full throttle before it would bog down. I am not a jet ski mechanic by any stretch of the imagination, however I am pretty handy and would love to learn to fix some of these problems as the arise.
The symptoms you describe sounds like it is in the carburetors. because of the age of the Sea Doo , I would recommend a carburetor rebuild and flush the fuel system plus check the check valves that are coming off the fuel tank.
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