Force engine bounce

Natalie

Recruit
Joined
Jul 12, 2001
Messages
2
I have a 1990 Force 120HP engine. When in water below 2000 RPM runs fine-above 2000 RPM in gear the motor bounces up and shakes. Out of water with hose hooked up no bounce. Transom at about 4 second interval will bounce again and again. Runs fine above 2000 RPM. Tried replacing Hub in propellar did not fix problem seemed to have gotten worse. Do you think this be an engine problem or lower unit problem? Can it be fixed without having to bring in to shop? Thanks for the help.
 

12Footer

Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: Force engine bounce

Bounce, shake, cough, sneeze,hickup...Run a can of engine tuner thru the engine.Then,change the plugs. Chances are, you'll not need to go further. I hope not, antway, as it get's expensive after that.
 

12Footer

Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: Force engine bounce

Forgot to mention, check the transom mounts too.Make sure they are tight,and waterproofed.
 

Natalie

Recruit
Joined
Jul 12, 2001
Messages
2
Re: Force engine bounce

Thank you for suggested, will definately try. Also forgot to mention that motor seems to pull away from hull when it bounces, shakes, coughs ect. Not sure if that made a difference in answer.
 

12Footer

Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: Force engine bounce

From what I have read here, the Force 120 has a problem with "sneezing" , especcially when cold. They must be decarboned often.<br />The fact that it's moving on the transom doesn't change the answers any, but in addition,you must find out why before leaving the dock again. Check the transom for rot under the fiberglass, and the mounts for snug fit.Make sure it is waterproof. If I were you,I would get a "survey" done. One of the first things they'll check is the transom and hull integrity. This is critical.<br />A spongy transom can fail in a split second,and your investment will sink on the spot.<br />The motor performance is very much secondary here.
 
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