1997 Speedster problem

[Lagwagon777]

I bought a Speedster in June of 2019, took it out on the river for a test drive first and it ran fine. Then after I bought it, I took it to the lake. It was having high rpm's and low power, I was told that is called Cavitation. When only 1 or 2 passengers (plus myself driving) the boat gets on step in 2-3 seconds. When I tried to pull my best friend on a slalom ski, it did not pull her out of the water. It pulls a tube just fine. I am 240 pounds and the skier was 175 pounds. I was told with 170HP, this boat should have no problem pulling a skier. So I took it to my local dealership, this is what they replaced and the labor they did:
3x o-rings
1 boot impeller
2x roulement bearing needle
1 housing-impeller
1 o-ring nitrile
1 impeller assembly
1 oil pump
1 oil seal
Replaced starboard side impeller and liner, filled and sanded jet housing, replaced bad battery switch, test run all good.
So after $1800 in parts and labor, I was excited to test it out with a skier. I got in on the lake and the exact same results. Ok with a tube, not pulling a skier. I am lost. This is my first boat, so I know almost nothing about the motor or impellers, how things should look. All I can think of it to remove the airbox on both engines and make sure the carbs are not gummed up (spray them with aerosol carb cleaner), test the plug wires to see if all the cylinders are firing. I don't know what else to do. Any suggestions? Please use very descriptive terms, because I have no idea what I am looking at.

 

[burtcanasta]

Maybe the people who fixed it missed something. I'd take it back to them and have them double check there work .

 

[POPPS]

Wow, mind boggling and ridiculous is my first response! Oil pumps have nothing to do with cavitation! Cavitation can occur with a worn/damaged wear ring, with a damaged prop, with a worn neoprene pump seal (or in some cases none at all), with the 2 seals in your carrier housing, with a cracked bellow, with a loose bellow, if you have a shaft protector, (to keep ropes from working their way up into the carrier bearing seal), broken ones also can cause cavitation, and lastly to my knowledge, it is possible that your ride shoe/plate is leaking, rare, but can happen. Changing bearings (2 of them), in the pump will not stop your problem.