1 reply to this topic

[kattwell]

When we start going for a bit one motor drops off and the other one increases in RPM. One runs about 3500 RPM's and the other 7000 RPM's. We can't seem to get both motors to work together. Sometimes when we are pulling someone on a tube we can't maintain constant speed. HAS ANYONE ELSE HAD THIS TYPE OF PROBLEM. What have you done to rectify this??

[tiggerman]

Sounds like one jetpump is cavitating, the other is hooking up as it should. Get a flashlight and look up in the pump on the engine that is revving to 7K, and see if you see anything (like rope) up in the pump. You may have to get underneath and look as well, paying attention to the intake of the affected side. The wear ring may also be causing this, and may have been damaged by rope or anything else that got sucked in the pump.
Common problem as the boat ages. One fix is to replace the driveline seals on both engines (where the driveshaft exits thru the hull)- another is to replace a neoprene seal where the pump mounts to the "shoe" on the transom. Lastly, replacing the wear ring(s) may solve it. Google " jet boat cavitation" and look at the returns.