Johnson 6HP Idle/Troll ?

[wdgold]

I have a 1965 johnson 6 hp motor. Runs great at high speed, but wants to quit at trolling or idle speed. I have adjusted the idle mixture the best I can, but it still will not run right at low speeds. This motor had a tune up in the last 3 years or so.

[boatfixer]

Spark, fuel, compression.

How does it quit? Does it sneeze and die or does it shut off?

The first thing that comes to mind is carburation. In particular, the low speed circuit. Its possible that it is gummed up a bit in the low speed passages. The packing around the low speed needle may also be leaking causing a lean condition. In either case, a good cleaning and rebuild will take care of it.

The other possibility is ignition. The stator plate moves as you twist the handle. It is not uncommon to have a worn spark plug wire and have the spark jump to ground as the stator plate is moving. Do a spark check with the throttle in a couple different positions. Excessive spark gap can cause problems as well.

I would lean towards carburation in this case but do spark and compression check to rule out other problems.

[wdgold]

I pulled out the needle valve for mixture adjustment and made sure it was clean at the seat and needle itself. I was able to adjust the mixture to a slow troll and it worked a whole lot better, I was able to troll without it stopping. And that was the only thing I did was pull out that needle valve shaft and then readjust the mixture.