Carb Guidance to fix cough/sneeze at idle.

[DougyB]

Hey guys, I was fishing the other day a few hours after putting threadlocker 290 self wicking formula around the carb gasket, where the bowl meets the upper carb body. It is suppose to seal any small air leaks that occur from the actual carb. I did it preventatively, but an hour into fishing it was coughing and sneezing bad at low idle. Im thinking maybe it seeped into the carb and some is stuck somewhere. Ran fine midrange to full. Today I replaced plugs, gas, and even swapped a spare powerpack, finally I used a spray bottle of premix while it was lean sneezing from exhaust which helped it purr like a kitten. So, my diagnosis is now a faulty low speed carb problem. My idle needle never moved, I tryed to adjust it anyway in small turns, with time in between, to no prevail... the sputtering didn't change.
So I took my carb off, bowl is clean as well as high speed jet. My problem lies in the fact I know nothing about cleaning the low speed portion of a carb. Its an 86 johnson 25 tecdc, I was hoping you guys could point out the most likely spot for a blockage or whatever is causing my coughing problem. I don't really know how to adjust the needle so that it seats either. I have heard of the upside down blow in/no air out trick, but thats just to check your work once everythings together. Any help is greatly appreciated, I'm not confident after reading the low profile carb readings. Heres a pic of my carb.

 

[Daviet]

Re: Carb Guidance to fix cough/sneeze at idle.

The static seting for the low speed needle is 1 1/4 turn out from lightly seated, and then fine tuned on the water in gear for best idle.
When you cleaned your carb did you remove the core plug on top of the carb and clean the tiny passages in there, that is part of your low speed circut.
To set the float level, turn the carb body upside down (float on top) , adjust the float so that the float is parallel to the carb body.
When you hold the carb in the upright position with the bowel on and blow into the fuel inlet you should be able to pass air. If you turn the carb upside down and blow into the fuel inlet it should not pass air. Do not use an air compresser to blow air into the fuel inlet.

 

[DougyB]

Re: Carb Guidance to fix cough/sneeze at idle.

Back from vacation, I took the carb off and cleaned every passage, including the three accessed via removing the top core plug. I also removed a side core plug and cleaned in there. I used 120 psi and small copper wire strands. Float was installed parallel and did not push air upside down. Put back on the motor today, fresh gas... it still coughs/sneezes. No matter what I do with the needle( besides totally screwing it in) I can't get the idle to change. As said before, spraying premix into the carb body fixes the cough. Any suggestions guys?

Motor runs good and strongat mid/high speed on water

 

[Daviet]

Re: Carb Guidance to fix cough/sneeze at idle.

Spraying fuel into the carb and the cough stops tells me you still a carb problem, running lean. Turning the low speed needle all the way in and it still runs tells me the idle circut is running lean. Did you check the little brass tube in the carb body, is it clean?

 

[DougyB]

Re: Carb Guidance to fix cough/sneeze at idle.

its as clean as I can tell. The real worries I have is where this penetrating oil could have got to... possibly up that long brass tube you mention. I have cleaned it with copper wires and air.The motor does shut off from 3 quarters turn out to all the way in. My other question I have....

I screwed the needle all the way out today to look at it, and there are two small cutouts on the needle. They are too small to take a picture of, both being about a 1/16th " square... and only about an 1/8" up from the end of the needle. I don't know if the needle came like this or erosion from gas took place, etc... But could this be my problem? Its almost like something scraped into the needle

 

[OptsyEagle]

Re: Carb Guidance to fix cough/sneeze at idle.

Sounds like your needle's cone has an indent in it. Is that what you are saying? If so, it is probably time for a new low speed needle. It probably came from someone seeting it tightly as opposed to lightly.

 

[DougyB]

Re: Carb Guidance to fix cough/sneeze at idle.

yes pretty much... more like a chip out of it than an indent. When the spitting/ coughing problem occured(two weeks ago after fishing for a while) the needle hadn't been touched in months... which leads me to believe its not the problem if erosion wasn't the cause of the ground parts of the cone.

 

[OptsyEagle]

Re: Carb Guidance to fix cough/sneeze at idle.

Did you use any carb cleaner when you cleaned the carb or just wire and compressed air. The reason I ask is if this 290 stuff got into your slow speed jet it might need to be dissolved away. Soaking it in carb cleaner or laquer thinner, or both, for a while might loosen it up and then blow the sucker hard with compressed air.

I would still be worried about that needle. They are supposed to be perfectly cone shaped. I can't say it is your problem but it sure might become one. Unfortuneately because those needles need to be so precise they don't give them away. Probably in the $50 range plus or minus a little.