9.9 HP Problem

[jyanna]

I have a 9.9 HP Nissan Outboard. The motor runs perfectly with the cover off, but is very sluggish and low RPM when the cover is on. Any ideas are appreciated.

 

[pvanv]

Re: 9.9 HP Problem

What is your model/serial? Model information is in the format NS9.9B2 or NSF9.9C, etc.

You likely have either a bad base gasket where the powerhead joins the exhaust housing (causing the carb to breathe exhaust when the cowl is in place), or a restriction (such as a wasp nest) in the air intake of the cowl, causing a lack of air when the cowl is on.

 

[jyanna]

Re: 9.9 HP Problem

I have a NS9.9B2. There is no air intake on the cowl that I can see.

 

[pvanv]

Re: 9.9 HP Problem

I have a NS9.9B2. There is no air intake on the cowl that I can see.

Not even under the aft tilt handle? The carb needs to get air from somewhere. It must come through either the upper or lower cover, or both.

If you see any smoke at all from near the base of the powerhead, you probably have a blown base gasket.

 

[jyanna]

Re: 9.9 HP Problem

Thanks so much for the help. I will check both of those out.