HELP!!!! RPM shoots up and boat barly moves

[rrim85]

I have a 92 speedster 5894 and it is not it is not speeding up when throttles are pushed up. It does fine til about 4000 RPM on each motor but once you push a throttle or both any higher, RPM's rise rapidly to about 7000 to 8000, motors are screaming like if you were running it at full power while in neutral but with a more force full sound, and the boat is barely moving. The only thing I have recently done to it is change the spark plugs and installed a battery selector switch so I can turn the battery on and off, on the boat without disconnecting them. I really have no idea what could be wrong with it or where to even start. It would really be appreciated if someone could help me with my little problem. Thank you.

 

[joshpxj]

not a expert but sounds like wear ring/ impeller to me. or debris in pumps. unlikely on both sides but...