Engine idles at low throttle, dies otherwise

[jkschneider]

Hi all,

I am trying to make a foray into boating and move over to the dark side of trotline catfishing on our local rivers.

I was given an old '63 fishing boat with a '70 5-horse Nissan 5BS outboard. It hasn't been ran in at least 2 years.

After getting rid of the rotten gas in the tank and siphoning the rest out of the fuel lines, I took the carb apart and made sure everything was clean (and sprayed and blew it all out anyway).

I put everything back together and adjusted the throttle stop screw to 2 turns from tight where it was before I started monkeying around with it and adjusted the needle valve to 2 1/2 turns where it was.

After some time, I was able to get it to start with the throttle at its lowest setting. The engine labors a bit to keep going and sounds very weak. When I make even the slightest adjustment to the throttle, the engine dies. I can start it back up with the throttle in the lowest position again.

I was led to believe elsewhere that the engine was probably running too rich? The plug was getting wet repeatedly and I kept drying it off before I got it going finally.

No adjustments to the needle valve seem to have any effect on the sound of the engine or my ability to increase the throttle.

Ideas?

 

[jkschneider]

As it turns out, there was a small piece of plastic that had broken off of the air intake to the carb and evidently gotten sucked through the carb. It was lodged in the cylinder valve, causing it to never close completely.

I just didn't see it until I was working on it out in the sunlight...

It's always something simple isn't it?

Jon

 

[Chris]

Hey Jon,

Glad to hear you got it sorted out - and thanks for posting up the solution, perhaps that will help someone else, somewhere down the line.

I didn't even realize that NIssan made outboards that far back.

What kind of ignition set up does it have?

Breaker points?

-Chris