Yamaha 9.9F Not Idling

marcb2001 · #1 July 17th, 2008, 03:41 PM

I have a 9.9 HP four stroke outboard on the back of my 27' sailboat. I am trying to get it to idle for more than 10 seconds. When I start it, the engine revs up faster and faster by itself and then dies. When I start it and cover the air intake on the carb with one hand I can keep it going semi normally for a short period of time. Should I open up the carb and try to clean out the fuel intake jets (I don't have the manual). Or is this a tough job to try on my own?
Marc

matt2002 · #2 July 17th, 2008, 03:59 PM

Make sure the choke is off.

marcb2001 · #3 July 17th, 2008, 04:33 PM

its an electric start with no choke. covering the air intake is in sense choking it

Yamajoe · #4 July 17th, 2008, 08:01 PM

Check your fuel lines from tank to fuel pump for restrictions and air leaks, ensure your tank air vent is open, the primer is firm and filter is clean; go to carb, on top of the carb, opposite the electrothermal (choke) valve you will see the air mixture (pilot) screw ensure that this is set at 3 turns out from lightly seated.

If this does not improve matters then a carb. overhaul is in order and while you are at it test the choke valve. the carb work is pretty straightforward but you should get a manual trust me it will pay for itself many times over.