9.9 johnson sputters running at times

[mrpike1973]

hi i have a 1975 johnson 9.9 moter i just had the carb rebuilt. i noticed when running it from wide open throttle to slow it sounds like it sputters a little then goes away. if i troll it will sputter not always but sometimes. i went back to the guy that fixed it said it had wrong plugs so i put the right ones in ran it tonight man does that thing have power however does the same thing some times. i put sea foam in the gas, fresh new non oxy gas any ideas i spent all my extra money to fix the carb. i dont think it will leave my stranded but? also it never did this before the carb rebuild bad carb?

[boatfixer]

It should have Champion UL81C plugs in it.

If it ran fine prior to the rebuild, It may only need the low speed mixture to be reset. Have you done this before? Pretty easy.

Turn the low speed mixture knob in until lightly seated **There may be a tab preventing you from turning in all the way, no biggie just pull knob out slightly**. Turn back out to about 1-1/2 turns. Start engine in a barrel/lake etc and let it warm up. Preferable in gear, while at an idle SLOWLY turn the knob in until it reaches its highest rpm and not that position. SLOWLY rotate counterclockwise to richen the mixture until it begins to stumble/idle rough then rotate back to the half way point. You can do it a few times until you get the feel of it.

[mrpike1973]

thank you thank you is the low idle speed the one on the front of the moter or the one on the side i will try this thank thank you for your response. i was unable to get champion plugs i got ngk but i ordered the champion plugs thanks very much!!!!

[boatfixer]

Part #13 is the low speed idle mixture knob

[mrpike1973]

thank you much i think i got it i hope thank you very much!!!!!

[Eelpout08]

good advice-low speed mixture screw is definitly the first place to start, if it sounds like a 'sneeze' every once in a while, escpesially when idleing that usually indicates a lean condition. one thing to keep in mind is on the carb there is a frost plug looking thing that needs to be removed in order to get at the tiny idle circuit pasages, otherwise it is very difficult to get any debris/varnish out of there.

[mrpike1973]

hi all after i adjusted it all seemed well. went back out today and had very hard time starting it then it wouldnt run good kept sputtering so i tried to readjust it didnt seem to help. this mixture screw is this on the carb? it just boggles me it always ran and started with not a hiccup now i dont feel comfy going any where

[jeffreyd]

sounds like whom ever rebuilt the carb needs to check the float to make sure it is in correctly. could be apiece of trash stuck in the jet too.