mercuriser 130 i/o shakes at 1000 rpm

[chubbybunny]

I have an 1989 mercruiser 130 i/o that shakes pretty rough at 1000 rpm. All four plugs are good and have spark and are geting fuel. WOT has good rpm and speed. After putting the drive in gear and giving it a little more throttle than idle it starts shaking hard enough to sake the whole boat, but continue giving it more throttle it smoothes out. It runs great and doesnt act like it wants to die. Could this be a timing issue?

 

[Silly Seville]

Re: mercuriser 130 i/o shakes at 1000 rpm

Has the engine always displayed this behavior, or is this a new problem? You could work through possible symptoms if this were a recent development. But if it's been an ongoing thing, it's a crapshoot. How much do you know about the engines history? Have you done the maintenance on it? There are so many things that could cause that run condition; and yes, timing is certainly one of them. Knowing its history would be a huge help in diagnosing the problem.

I'm just taking a shot in the dark here, but my first guess would be fuel system related. Bad timing is an issue that you would have noticed for a long time; but fuel issues can pop up suddenly with little warning. Especially with carbed engines.

 

[chubbybunny]

Re: mercuriser 130 i/o shakes at 1000 rpm

I've had the boat for three years and this shaking started at the end of last season. I've done the general maintance on it - plugs, wires, winterizing, ect. Its never overheated and always ran great. I got it up to temp and adjusted the mixture by the book and it helped for idle rpms but its just at around 1000 rpms that it really shakes. Also, one thing that I noticed is a slight hesitation when going from idle to full thottle..... carb overhaul time?

 

[tpenfield]

Re: mercuriser 130 i/o shakes at 1000 rpm

Let's take a look at what is holding the engine to the boat (and what is not). Perhaps something has come loose.

 

[achris]

Re: mercuriser 130 i/o shakes at 1000 rpm

I've had the boat for three years and this shaking started at the end of last season. I've done the general maintance on it - plugs, wires, winterizing, ect. Its never overheated and always ran great. I got it up to temp and adjusted the mixture by the book and it helped for idle rpms but its just at around 1000 rpms that it really shakes. Also, one thing that I noticed is a slight hesitation when going from idle to full thottle..... carb overhaul time?

Maybe check compressions, but that sounds very much like progression holes ('off-idle') are a bit gummed up and not allowing the correct mixture. Time for a carb strip and clean? Yep... If it's not been done before and is coming up 23 years old, you've done well...

Chris......

 

[Secondbestday]

Re: mercuriser 130 i/o shakes at 1000 rpm

I have been battling something very similar. Idles fine and up to 1000 PRM or so. From 1000 - 3500 rpms, rough running with increasing and decreasing rpms. I was just about pull the carb again and redo my carb rebuild, when I decided to change spark plugs. I simply pulled the old and installed the new. Perfectly smooth all the way up to WOT and back. If I were you, I would change the plugs and the wires even if new. Just to eliminate this.
Good luck,
CL