'96 Yamaha Troubleshooting Question

[waterbill]

This engine runs fine at idle speed and up to 1700 RPM. From 1700 to about 2200, it runs very rough; and then above 2200, it smooths out again. Has anyone had a similar problem, and where should I look for the solution?

 

[John from Madison CT]

Re: '96 Yamaha Troubleshooting Question

Sounds about right for these engine, as they don't use all 6 cylinders all the time.<br /><br />Go to: www.boatsetup.com and go to the Yamaha forum.<br /><br />They will help you there.<br /><br />John

 

[waterbill]

Re: '96 Yamaha Troubleshooting Question

Thanks for the reply, John. I did not know that about the six cylinder Yamahas. However, I should have given more details about mine. It is a three Cyl. 90 hp. It is very rough running between 1700 and 2200 RPM. Someone told me it sounded like a carburetion issue, but I have no idea. I've never owned anything this modern, and neither have I owned anything with more than one carburetor. In fact, I can't even find where the choke is for this engine. There is a toggle switch on the console throttle control, which the seller told me was the choke switch, but when I toggle it, nothing happens that I can see or hear.<br />The engine starts just fine, with or without my using this switch. What's up with that? Any advice will be greatly appreciated.

 

[redyute]

Re: '96 Yamaha Troubleshooting Question

i ran two 90hp Yami's on two 17 foot wailers and have experienced the same,but for me it was only a slightly damaged prop which vibrated at low rmp.

 

[rodbolt]

Re: '96 Yamaha Troubleshooting Question

hello<br /> most 90 hp motors of that year had prime start. it is an auto choke system. yes carbs would be the first place I would look.the manual choke lever is the tiny red tag on the front port side of the airbox, if the motor is not prime start then it will have a choke solinoid monted on the intake area.<br />sounds like maybe a problem with the intermediate air circuits<br />good luck and keep posting