1978 Johnson 9.9 runs only if choke is pulled out a little.

[E.Pruitt]

My brother just bought a 1978 johnson 9.9 outboard.It only stays running if the choke it slightly pulled out.The guy he bought it off of rebuilt the fuel pump himself.My brother said the man rushed the rebuild job,and may not have put a spring in correctly.Would this be the reason the motor will only run with the choke pulled out,or could it be a carb problem.Thanks to all who reply.

 

[joereeves]

Carburetor is either fouled or out of adjustment. If adjusting (as follows) doesn't help, remove, clean, and rebuild it using a complete carb kit.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[E.Pruitt]

Thanks Joe!!