RE: Unofficial
Sounds like you have a couple of different problems. The shaft bore tolerance seems to be critical in this jet drive and wear can lead to air entry causing loss of prime, as well as water entry when setting still. This is why it is so important to keep the shaft lubed with a good waterproof marine grease. Though some have relined with success, at this point I would buy another pump, keep the shaft greased and be done with it. Your motor seems too high a KV for 3S. Go with something around 3000kv and it should settle down without much (if any) loss in speed. Something I found out a while back was this boat goes through stages with increased speed. Given more speed, it porpoises, a little more speed and it settles down. You're in-between with your setup is all. Good luck!