Strange Idle Speed Problem on 1994 115HP Evinrude

[Jon Boat Jim]

The idle speed of my 1994 115HP Evinrude significantly decreases when I put the cowling back on! It will run relatively smoothly at about 900-1000 rpms with the cowling off. However, after I replace it the rpms drop by several hundred and the motor runs rough and wants to stall. At higher speeds all seems to be OK. What's happening? How can I fix it?

 

[Chris1956]

That is the classic behavior of an exhaust leak into the cowling,. An exhaust leak will starve the motor of oxygen. Check the powerheadbase gasket and any exhaust hoses under the cowling for a leak.

 

[Jon Boat Jim]

That is a great suggestion!! Thanks for your response.

 

[flyingscott]

You could also have partially blocked hood vents or your air box could be restricted.

 

[racerone]

Possibly spark is shorting out to the metal brackets of the cowling latches.-----Replacing plug boots and wires might be in order if there are no exhaust leaks.

 

[Jon Boat Jim]

Good suggestions from everybody! Thanks!