1996 GTX erratic RPMs while pushing Shuttlecraft

[MjC2810]

I have a 1996 Sea-Doo GTX that seems to run great by itself. I purchased it this spring and the previous owner had the fuel lines changed, carbs rebuilt and wear ring replaced. I purchased the ski along with a 1997 Shuttlecraft Jet Sport. While on the water, solo, the ski performs well. I haven't noticed any issues. Great throttle response, no bogging. One thing I've observed is that the inlet grate has a tine missing.

Issues arise when the ski is docked into the Shuttlecraft. While slowly trying to get out of the hole, the speed and RPM increase to a point (around 5100), where the ski then erratically jumps up and down in RPM. 5200 to 5700 to 6200 and up and down, all over the place. Getting the boat on plane requires a lot of feathering the throttle and it is not always successful. Sometimes it'll get up on plane after feathering and other times the engine is being so erratic that I don't want to push it and just drop down to a little above idle speed. Again, this issue does not present with the ski solo...

I pulled the carbs off and checked the filters - clean. Fuel filter is clean. Fuel selector valve is clean. R.A.V.E. valves have been pulled, they had carbon build up. I cleaned them and re-installed with a new bellows kit. For the Shuttlecraft, I installed spring loaded trim tabs thinking it would help. It has not.

Any thoughts? Cavitation occurring because of the Shuttlecraft?

 

[Nilet6149]

With the shuttlecraft hooked up, you may be at a higher plane than normal for a longer amount of time, and I’m wondering if your water separator is having some cavitation? Not common, but mine had a bad seal with crappy old worn out threads and O ring and it was doing the same thing more or less when I’d have someone on a wakeboard or ski.

May explain why it’s only with the shuttlecraft?