1996 Johnson 30HP only idles....

[1996JOHNSON30HP]

I have a 1996 Johnson 30HP model J30RLEOB. It will only idle with the primer (choke) open...close the primer and she rev's, than dies...have cleaned carb completely with OMB cleaner...checked the fuel pump for gunk...dismatled the carb 3 times and checked everything again...where are the high speed jets?..all I have are 3 tiny holes through the top of the casting into the throat...growing very frustrated.

 

[jegervais]

Re: 1996 Johnson 30HP only idles....

Did you remove the carb from the engine and COMPLETELY dismantle it, or did you just take the cover off?? The main jet is screwed into the bowl. Shutting off like that would indicate the main jet or idle pick-up tube is blocked, or the nozzle well gasket is missing (round gasket goes around brass tube). The other possibility is the idle needle is almost completely seated and needs to be adjusted correctly.<br /><br />-John

 

[1996JOHNSON30HP]

Re: 1996 Johnson 30HP only idles....

Thanks for your response...yes, I completely removed the carb and dismatled (3 times)...If the main jet is screwed into the bowl, I can not locate it...the bowl has a line coming in from the fuel pump (rear) and a line going out to the primer pump (front). In fact, the microfiche I saw at the parts counter does not show a high speed jet. There is a large tube on the bottom of the main body that opens into the throat with a thinner tube running thru the middle to the top of the body. At the top of the main body are 3 very tiny holes through the body into the throat of the carb...I have poked thin wire thru 2 of them....the 3rd is too small...It appears that the thinner tube running from the bottom to the top feeds fuel up to the top where the 3 holes are located. I was also told that the engine is a 1995, but the picture of the carb is more like a 96 which is much simpler. Any other insight?

 

[G DANE]

Re: 1996 Johnson 30HP only idles....

Hi <br /><br />If you remove the drain screw from the buttom of the bowl, you will find the high speed jet located in same threads, in behind the drain screw. Unscrew it and clean carefully.

 

[jegervais]

Re: 1996 Johnson 30HP only idles....

The jet is behind the fitting that supplies the primer. Remove the hose, unscrew the fitting and look inside. You'll need a narrow screwdriver to remove the jet. Be careful not to ding up the threads of the carb bowl, they recommend a special tool for this, but with care a screwdriver will work. The only other insight I have is the adjustable idle needle.<br /><br />-John

 

[almost retired again]

Re: 1996 Johnson 30HP only idles....

I agree with all of the above post. The three small holes that you are talking about are the idle feed and holes that enter the throat behind the throttle plates. All fuel that is supplied to te carburator must come thru the high speed jet first. The small tube that runs completly thru the venturi to the top of the carb. body supplies fuel to the idle and intermediate circuits. The larger tube that ends in the venturi is what furnishes most of the fuel during high speed operations. Like most of the rest have said, clean the hi speed jet,and make sure the boss gasket is in place.<br />Just my thoughts

 

[1996JOHNSON30HP]

Re: 1996 Johnson 30HP only idles....

Thanks to all of you...I will remove the front fitting the feeds the primer and take a look....I have blown cleaner through that area already and pushed a wire thru without resistance...Question: What is the boss gasket? "Almost Retired" mentioned it...I have a new gasket kit but no instructions....I also have a round gasket that appears to slide over the large venturi tube....the center hole is in the shape of a star...it does not appear to provide any gasketing features...Thanks again!!!!!