bought old boat last week and motor shakes the whole boat at lower RPM.

[12thManFalseStart]

73 johnson, on 17 foot boat. 115 hp, and I've noticed it shakes bad under 2,200 rpm while in gear. Idles ok, and slowest is ok, but when I give it gas "not hole shot power" but slowly, it starts shaking and acting like it doesn't want to go, but after up to the 2,ooo plus RPM, it's fine. Carb problems maybe? I was hoping it wasn't a bent shaft, but wouldn't that shake at all rpms pretty much?

 

[Daviet]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

I agree, a bent shaft would vibrate all the time.
Have you done any checks, compression or spark?

 

[pn]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

if you have the time and skills, go through your carbs.

 

[12thManFalseStart]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

Would you guys recommend running that seafoam through it? I've only seen this done on cars on youtube, and makes it smoke, but I'm still not sure this is great to do to your engine. Maybe just dump some in the tank instead of dumping it straight into the throttle body.

 

[willy007]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

It's better to completely disassemble and clean or rebuild them altogether. Seafoam won't really clean the carbs the way that they need. The jets or passage ways could be gummed up or a piece of debris could be lodged.

Have you checked for good spark on all cylinders? You may be missing due to a poor spark.

I agree, it's probably not a bent shaft as it would shake consistently.

 

[Daviet]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

If your carbs are dirty, sea foam will not clean it out, might help to keep it clean. The only way to clean them is to take them apart and do it properly.

 

[12thManFalseStart]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

Do you think putting premium gas in it would help? I just noticed while reading the manual, it calls for no less than 94, and I've been putting in the lowest, 87 I believe it is. God, like it's not already expensive enough for the cheaper gas. Think I would notice any more power, or just a lighter wallet? lol

 

[pn]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

if you don't want to take anyones advice...good luck.

 

[willy007]

Re: bought old boat last week and motor shakes the whole boat at lower RPM.

Do you think putting premium gas in it would help? I just noticed while reading the manual, it calls for no less than 94, and I've been putting in the lowest, 87 I believe it is. God, like it's not already expensive enough for the cheaper gas. Think I would notice any more power, or just a lighter wallet? lol

You may not notice an increase in power but it may help run smoother... Using premium wouldn't be a bad idea, especially if you live somewhere where the premium does not have ethanol added! Either way though, if your carbs are that dirty or clogged, it won't matter what kind of fuel you run until you clean them.