Another 9.5hp Johnson question...

[dfrants]

got a 1973 9.5 Johnson that I replaced the points, condensers, spark plugs, needle and float. I took the carb apart and cleaned it, it wasn't dirty. it starts and runs good until you idle it down. It will idle a troll smooth for a minute or two then slow down on its own and either speed back up and keep running or just die out. Starts right back up with one pull. It only does this at a slow speed. It accelerates and runs full speed great. What could cause this ?

 

[gm280]

dfrants, could be the low speed jet circuit or the idle mixture screw needs adjustment. Not a big deal, just a little adjustment. But turn the idle mixture a little at a time and let it smooth out to see if that works. Don't turn it more then about 1/8 of a turn or so at a time and let the idle mixture smooth out before turning again... JMHO!

 

[Chinewalker]

Float level set correctly?

 

[reiddo1]

got a 1973 9.5 Johnson that I replaced the points, condensers, spark plugs, needle and float. I took the carb apart and cleaned it, it wasn't dirty. it starts and runs good until you idle it down. It will idle a troll smooth for a minute or two then slow down on its own and either speed back up and keep running or just die out. Starts right back up with one pull. It only does this at a slow speed. It accelerates and runs full speed great. What could cause this ?
Are you running the engine in a test barrel with the engine cowling on? If so try the same with the cowling off and see if there is any difference. Mine behaves the same in a test barrel, but on the boat is completely different. The carb seems to be sucking in exhaust gases in the barrel whereas on the boat it is not. Just a theory which works for me.

 

[dfrants]

I also noticed that difference. but, it is also doing it out on the lake...

 

[racerone]

Will spark on this motor jump a gap of 5/16" with a snap you can hear , yes or no.