1995 Evinrude Ocean Pro noise

[esto99ca]

Hi I am new to this forum and I have a question.<br /><br />I just bought a ReefRunner 17' with a 1995 90HP Ocean Pro. It starts great and runs great. However when I throttle back there is a sound coming from the motor that sounds like metal flapping. If I throttle down slowly the noise is not present. The noise is not there on throttle up. I am running at 4000-4500 rpm when I throttle back. Prop is 15x17 and WOT rpm is 5000. Has new plugs and water pump.<br /><br />Anyone have this problem or is this normal?

 

[clanton]

Re: 1995 Evinrude Ocean Pro noise

Slow down slowly, try larger midrange jet. There was a valve setup on the V8, to add fuel, when backing off throttle. You might graft this on the 150.

 

[esto99ca]

Re: 1995 Evinrude Ocean Pro noise

Thanks Calnton - but as a novice I really don't understand the reply. It is a 90 HP V4. Do you know what is causing the sound and will I damage anything if I don't have it serviced?

 

[angus63]

Re: 1995 Evinrude Ocean Pro noise

Rapid throttle deceleration causes out of time detonation until the rpms come down equal to the throttle position. Inherent on all outboards with timing advance/throttle combo. Unless it's an emergency, throttle back easy and you'll never hear the clacking.

 

[clanton]

Re: 1995 Evinrude Ocean Pro noise

The prop continues to spin engine, after the throttle moves back causing a lean condition, and the engine knocks fron detonation. I have only heard this on the 60 degree engine, If you have a 90 degree cross flow, may be different problen. I also thought the 90HP Ocean pro engine was a 60 degree engine. I will check for more information, but sometimes I forget. Bump back to top. I hope to have my computer running next week, I will have easy excess to my manuals.

 

[esto99ca]

Re: 1995 Evinrude Ocean Pro noise

Can I get this fixed this or just live with it?<br /><br />Can I damage the engine? <br /><br />I would have thought a lot of people would complain about this to OMC!

 

[seahorse5]

Re: 1995 Evinrude Ocean Pro noise

Your "stack fire" noise is noticable in some applications, and is only in the 60 degree block engines from 90 thru 175hp. An easy fix is to reduce the size of the carburetor's mid-range air-bleed jets about 4 sizes. That richens up the mixture a bit above idle to help minimize the "stack firing" noise.

 

[esto99ca]

Re: 1995 Evinrude Ocean Pro noise

After running the boat now for a few days I find that when I am ready to throttle down, if I trim down first the decell knock goes away. So trimming down must slow the prop.<br /><br />Thanks to all the respondents.