Re: 9.9 Johnson Carb Question

[David Stanton]

OK – that stuff on heads was interesting and I learned a bit there – Thanks!
–
Now back to my original 9.9 idle problem. I got psyched up to work on it again and I’m finally getting somewhere. I swapped a carb from a good idling 1989 15 HP and it idled super-good. So looking further into the 1977 9.9’s carb, I found there was no bearing on the needle; and remember I got a piece of glop out of the needle-end of the housing the other day, so that was some of the problem too, as it was up by the needle. The carb bowl , needle/seat. etc when I first took it apart was very dirty and the float needle was jammed with crystalized stuff, so I got to looking at the passageways from the bowl to the low speed needle again, figuring there was probably dirt everywhere, even though I had previously run some carb cleaner through all the openings I could find. I’m trying one last time to avoid pulling out those lead shots. I have the welch plug off the mixing chamber and have verified the three holes to the throat are clear, and hole to the needle is clear.
–
I determined that part way up the cast tube that hangs through the center of the float, downstream of the high speed jet, there are passageways on each side just above where the brass venturi tube hangs down and ends. One goes up to the bowl vent that is on the carb throat opening rim. I backflushed that with carb cleaner, and passageways are well open. The other passageway next to the brass tube goes through the carb casting up to the low speed needle. I bent the carb cleaner plastic tube slightly on the end about 60 degrees and put it up in the needle housing trying to get it to find the opening where the gas comes up. After moving it around some while spraying cleaner, I hit the pasageway dead on and was able to backflush the gas idle passages back down from the needle housing into the bowl big time – I didn’t see if any dirt came out because I was standing outside holding it away from me, but now I’m reasonably confident that the idle gas passageways are open and clean. So tomorrow, I will put it back together with the new bearing in the carb kit and see how it does. If that fails, I will pull those lead shots to make darn sure all the idle gas passages are clean.
Dave