No power under load

[gcmart]

I have a 2005 suzuki 115hp which will only go about 8 knots in the water. I have pulled it out and found that the butterfly valve isn't opening but when the engine is off and I put the throttle down it is opening fully. Any help would be greatly appreciated

 

[99yam40]

I have a 2005 suzuki 115hp which will only go about 8 knots in the water. I have pulled it out and found that the butterfly valve isn't opening but when the engine is off and I put the throttle down it is opening fully. Any help would be greatly appreciated

Not much info,
what did you pull out

what do you mean by when the engine is off and I put the throttle down it is opening full?
motor off the boat?
motor not running?
key is in the off position?