Vibration 1500-2000 RPM - force 70HP

[Berke]

Hi All,

I have a force 1992 70 HP and since this weekend it's making more noise and has vibrations in the 1500-2000 range. Strange thing is that its not happening all the time. Once passed the 2000 RPM's it runs great. Also no problems with starting or idling and prop is not damaged. Any idea's what's causing these vibrations? Thanks.

 

[john from md]

Re: Vibration 1500-2000 RPM - force 70HP

It could be that one of your cylinders is starting to misfire or run lean. Either will cause the engine to vibrate and kick. Make sure your fuel lines, tank and carbs are clean before you do anything else.

Report back,

John

 

[dst87mcssac]

Re: Vibration 1500-2000 RPM - force 70HP

Hello,

My 1997 Force 75 HP on a 22 foot Crest II Pontoon does the same thing. It seems like I learned on this site several years ago that it is because my motor has only one carb. By only having one carb the motor does not like that particualar RPM Range. However, it may have been the boat dealer ( Force / Crest) that told me that. I can not remember, but I am thinking that mine does it because of the one carb. Once you get a little bigger Force Motor you then begin to have three carbs. Mine too runs great once you increase the RPMs.

Just one more reason these motors were price leaders.

I hope this helps,

Donald

 

[Berke]

Re: Vibration 1500-2000 RPM - force 70HP

Hi! Thanks for the info. I think (or I hope) I found the problem. There were 2 loose bolts on the bracket that holds the trim piston. Will test it over the weekend.