99 seadoo gti 717

[stang7tl]

ok well this ski will run fine I will run a half a tank out and do 50 mph and then it will only go 25-35 and then 10-15 what could be the issue? the carbs were rebuilt gas tank was cleaned and the fuel lines were replaced. Could it be a over heating? But when it acts up I opened it up and the engine was not hot I could easily touch the block. Are mechanic has done several thing but is happens. Please help

 

[kustomkarl]

It sounds like the fuel vent valve is partially clogged. Next time you run it open the fuel tank cap and listen for a vacuum. Also what do the spark plugs look like when it has this problem?

Karl