1998 9.9hp mercury dies

Dhoitsma

Recruit
Joined
May 6, 2015
Messages
1
I have had tons of problems getting this motor since purchasing the boat a few years ago. Finally received a tip for starting that works great (pump the throttle fifteen times before trying to start) but it doesn't want to stay running smoothly. I fired it up this spring and noticed when I take the cowling off it runs much better. As soon as I put it back on it starts to choke down like it is not getting air. Anyone else have problems with this or any ideas? I also had lots of trouble last fall with the speed fluctuations. I am thinking this may be related to the lack of oxygen that I am fighting now. Any pointers would be appreciated.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
One common cause of running better with the cowl off is a leaking base gasket. The exhaust fumes get sucked back into the carb and create the problem. These are normally very good motors, so having lots of issues is a little odd.
 
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