1989 Force 150 rough at full throttle

[gunner_mn]

I was able to get the boat on the water this weekend and it isn't running right. It works well up to about 3500 RPM and then it starts cutting out, misfiring or sounding like it's over revving. Hard to describe the sound. Last fall I brought it to a tech school here and they went through it and fixed all the electrical components of it but they ran out of time to fix everything. So I would think spark would be good and I checked compression before I brought it in and as soon as they were done it went into storage for the winter. The instructor there said he thought there might be an exhaust leak I believe? It seems like it's more than that to me. Anyone have thoughts on what could be causing this?

I also have a video of it running on the lake. It occurs at about 4 to 8 seconds and then at about 15 seconds again. It's not off and on it's from me pushing the throttle farther forward. http://www.youtube.com/watch?v=XKFOKvMRDbA

 

[Robert D]

Re: 1989 Force 150 rough at full throttle

Check the carbs for a restricted jet......

 

[jerryjerry05]

Re: 1989 Force 150 rough at full throttle

First check for water in the fuel.Then check/replace the hoses for soft/mushy or loose connections.
Any inline connectors? Remove them,they can suck air.
Then rebuild both pumps.Clean the carbs.Install a filter between the last pump and the carbs.
Do another comp/spark test.After all students were working on it.
At the top of the Force section is a thread by FrankA. It explanes a link and sinc.
Then set the air screws.In till they just bottom out then out 1 and 1/8turn.
Then fill out the profile,you might be close to someone who can help.
Oh yea put in a water/fuel seperating filter.Jerry