1969 Johnson 20 hp Dies on Slow Idle

[John Drew98]

I rebuilt the carburetor and put in new gas pump. Starst easily if I choke it but always have to choke even if has run for 5 min. I turn the gas throttle handle as far as it will go in the start position, choke it and it starts without any issues. If I turn the gas throttle down 1/4 turn it starts to hi-cup an will die and will if if don't turn it back up. The slow speed needle may be the issue but it's 50 years old and they don't make them any more. or perhaps the carb since I always have to choke no matter what but I rebuilt it. When I put in gear and open up runs perfect no misses or hi-cups. I did replace the oifice plug , which is at the bottom of the carb, when I rebuilt the carb.

 

[racerone]

Open the slow speed mixture screw 1/8th turn at a time and see if the hik-up goes away.

 

[NicoPags]

https://forums.iboats.com/forum/eng...sorted-carb-variations-by-joe-reeves?t=167352

I would go through the slow speed adjustment as Racerone suggested

 

[John Drew98]

Thanks Racerone for sharing your expertiese. You have a vast source of valuable information for the novice like me. I turned the slow speed idle twice at 1/8" each and on the second turn it stopped the hik-ups. I had started at 2 full turns out to begin with.