motor help

Need some help here. Before I take it to someone I don't know I'm looking for info that will help me fix it myself or allow me to not look or sound stupid when i go to the mechanic about the issue.

I have an older, carb'd 150 HP merc. It has sat for a while so I decided to bring it home and work on it some. Changed the gas. Plugs looked good, clean. Started the motor. Takes a few turns to get it to turn over. I notice excess fuel coming from the carb cover.

This is where I become clueless. It won't run for more that an minute at most. if I forward the throttle it will run at the higher rpm's NP. If I back it off to the idle position it quits.

Havn't gotten any further at this point.

Any help would be great.

Carb jets are varnished.

Just below the throttle plate is the idle circuitry. This is a common problem with carburetors that have sat unused for long periods of time. The remaining gasoline in the system dries out and leaves a varnish type deposit that clogs these passages. Only solution is to take them off and have them cleaned and rebuilt. It is more than installing a rebuild kit, because they need to be soaked first in a strong carburetor cleaning solution and then blown out with compressed air. Depending on how mechanical you are, you could take them off and have them professionally rebuilt, and then reinstall them yourself. Happy motoring.

Thank you for the info!

Any thought on what it should cost to rebuild if I remove and reinstall myself?

For anything carb related, I'd take it to a proffesional experienced with dealing with higher hp outboards. If you do it yourself and setup one of the carbs wrong, you risk leaning out a cylinder and taking out a piston. I just went through this with my old 60hp outboard.. Thought I had the carbs set right as all I did was clean them and reset them as close as to where they were and wound up taking out the top cylinder.