2004 150 jumps up rpms w/o touching throttle

[JPCala]

I have a 2004 Yahama 150 hp outboard model # 150txrc. I noticed that the engine will suddenly jump up another 1000 to 1500 rpms without me touching the throttle. I ran it at top speed at about 5200 rmps and the the next day it would not get over 4700 rpms. Any suggestions, is this a problem that might be a cheap fix or will I need a mechanic? THANKS John

 

[mpeel63]

Re: 2004 150 jumps up rpms w/o touching throttle

I am experiencing something similar with a 1998 Merc 115. I get to about 5000 RPM and it jumps 1000 to 1200 RMP and I have to back down. to stop it from revving. The speed obviously doesn't jump.

Can anyone offer a sugestion/guidance for either of us?

Thanks!

 

[JUSTINTIME]

Re: 2004 150 jumps up rpms w/o touching throttle

sounds like an air leak or running lean