Johson 8hp idle problem

Hello, I have a 2001 Johnson 8hp. When it is in neutral it will idle with the throttle all the way back. but when its in gear and i try to idle it really low it dies out. It is a pain when I am trying to troll because it will idle for a little bit then start to die out. Do I need to clean the carb?

Re: Johson 8hp idle problem

Won't a small increase in the idle speed setting do the trick.

Have you also tried tweaking the slow speed mixture adjustment to see if that helps.

Re: Johson 8hp idle problem

I haven't tried anything really ive only had it for 2 weeks and have only had time to go out twice. and I dont keep the boat at my house. I will try to adjust it next time.

Re: Johson 8hp idle problem

With the cowling off, and the engine running in the water, turn the idle adjustment knob on the end of your tiller handle until the engine is idling in gear at the rate you want. Watch what moves on the carburetor linkage. There's an idle stop screw in that linkage. When the idle speed is right, adjust that idle stop to touch the linkage.

It won't take much to bring it to the right idle speed.

The 6hp and 8hp have that handy knob to allow anglers to adjust trolling speed. It's a neat feature, and it makes idle adjustments a snap.

Re: Johson 8hp idle problem

I am pretty sure the carbs need a cleaning the last time was about a year and a half ago. Has anybody used seafoam? I have used it in cars but wasn't sure since its a 2 cycle if it would work... i don't want to run it and not have proper lubrication.

Re: Johson 8hp idle problem

If it runs well and if it idles well when not in gear the possibility that it needs the carb cleaning is small.

Heavens its practically new. I have not yet had to clean the carb on my 1984 6hp but perhaps we get decent fuel in the UK.

Try the adjustments first. If you can set it so that it does not die using the adjustment knob on the tiller then problem solved.
As I said earlier you can try the mixture adjustment screw on the carb.
See the Engine FAQ HERE for the full details.

If you cannot get it to idle properly with a combination of those two then it's the time to consider a carb clean perhaps. That means dismantling and cleaning properly not just waving a can of carb cleaner around near it.

If you use Seafoam in the fuel you still use the normal 50:1 fuel oil mix and add the Seafoam to that.

Re: Johson 8hp idle problem

Alrighty. I think its just the idle adjustment because if i advance the throttle a but it runs fine.

Re: Johson 8hp idle problem

I raised the idle but still get the problem occasionally where it will just die out like its not getting gas. maybe i will have to try the mixture screw.

Re: Johson 8hp idle problem

Do you have a picture of what the knob looks like. I think I know what knob you are talking about but I haven't been able to go check it out I have been too busy.

Re: Johson 8hp idle problem

If you're talking about the slow speed adjustment, you'll find the knob on the tip of the tiller handle. Clockwise will speed the engine up. Counter-clockwise will slow it down. It's designed for use while trolling, to make fine adjustments in the engine speed.

There is an idle stop adjustment on the carburetor as well. With the throttle at its lowest setting and the slow speed knob turned fully counter-clockwise, you can adjust that screw to the minimum speed that allows the engine to run smoothly in gear. It's on the side of the carburetor.

The idle mixture screw, which controls the air:fuel mixture at idle is on top of the carburetor. You may be a bit rich on that one. Clockwise to lean out the engine at idle. Counter-clockwise to richen it. Adjust this in small increments (1/8 turn), then wait for the engine to adapt to the new adjustment. At some point, as you go lean, the engine will speed up a bit. A little further, and it'll cough or sneeze. Back the needle out 1/8 of a turn at that point and you'll be good to go.

The combination of those two adjustments should give you an idle, in gear, that lets the engine just putt along. When you get it right, you'll be amazed at how slow you can idle.

Re: Johson 8hp idle problem

Thanks cat. I really appreciate the help.